diff --git a/base/trace_event/brave_process_memory_dump_unittest.cc b/base/trace_event/brave_process_memory_dump_unittest.cc
index b09edc31f24..d0e2bc23065 100644
--- a/base/trace_event/brave_process_memory_dump_unittest.cc
+++ b/base/trace_event/brave_process_memory_dump_unittest.cc
@@ -6,8 +6,7 @@
 #include "base/trace_event/memory_infra_background_allowlist.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
-namespace base {
-namespace trace_event {
+namespace base::trace_event {
 
 TEST(BraveProcessMemoryDumpTest, IsMemoryAllocatorDumpNameInAllowlist) {
   // reset the test allow list leftover from other suites
@@ -32,5 +31,4 @@ TEST(BraveProcessMemoryDumpTest, IsMemoryAllocatorDumpNameInAllowlist) {
       "extensions/value_store/Extensions.Database.Open.BraveWallet/0x1234"));
 }
 
-}  // namespace trace_event
-}  // namespace base
+}  // namespace base::trace_event
diff --git a/browser/ethereum_remote_client/features.cc b/browser/ethereum_remote_client/features.cc
index 4993c341ec6..3a5bcb146d6 100644
--- a/browser/ethereum_remote_client/features.cc
+++ b/browser/ethereum_remote_client/features.cc
@@ -7,12 +7,10 @@
 
 #include "base/feature_list.h"
 
-namespace ethereum_remote_client {
-namespace features {
+namespace ethereum_remote_client::features {
 
 BASE_FEATURE(kCryptoWalletsForNewInstallsFeature,
              "CryptoWalletsForNewInstallsFeature",
              base::FEATURE_DISABLED_BY_DEFAULT);
 
-}  // namespace features
-}  // namespace ethereum_remote_client
+}  // namespace ethereum_remote_client::features
diff --git a/browser/extensions/api/brave_shields_api.cc b/browser/extensions/api/brave_shields_api.cc
index 21efd30ad0b..0cc5cb1c60c 100644
--- a/browser/extensions/api/brave_shields_api.cc
+++ b/browser/extensions/api/brave_shields_api.cc
@@ -18,8 +18,7 @@
 #include "chrome/browser/ui/browser_finder.h"
 #include "components/content_settings/core/browser/cookie_settings.h"
 
-namespace extensions {
-namespace api {
+namespace extensions::api {
 
 ExtensionFunction::ResponseAction
 BraveShieldsAddSiteCosmeticFilterFunction::Run() {
@@ -44,5 +43,4 @@ BraveShieldsOpenFilterManagementPageFunction::Run() {
   return RespondNow(NoArguments());
 }
 
-}  // namespace api
-}  // namespace extensions
+}  // namespace extensions::api
diff --git a/browser/extensions/api/brave_talk_api.cc b/browser/extensions/api/brave_talk_api.cc
index 35a38d46ed7..4ccf3e5f6da 100644
--- a/browser/extensions/api/brave_talk_api.cc
+++ b/browser/extensions/api/brave_talk_api.cc
@@ -11,8 +11,7 @@
 #include "base/environment.h"
 #include "chrome/browser/profiles/profile.h"
 
-namespace extensions {
-namespace api {
+namespace extensions::api {
 
 ExtensionFunction::ResponseAction BraveTalkIsSupportedFunction::Run() {
   Profile* profile = Profile::FromBrowserContext(browser_context());
@@ -24,5 +23,4 @@ ExtensionFunction::ResponseAction BraveTalkIsSupportedFunction::Run() {
   return RespondNow(WithArguments(true));
 }
 
-}  // namespace api
-}  // namespace extensions
+}  // namespace extensions::api
diff --git a/browser/extensions/api/brave_theme_api.cc b/browser/extensions/api/brave_theme_api.cc
index e3b3f4a38eb..5d36ed01629 100644
--- a/browser/extensions/api/brave_theme_api.cc
+++ b/browser/extensions/api/brave_theme_api.cc
@@ -14,8 +14,7 @@
 #include "brave/browser/themes/brave_dark_mode_utils.h"
 #include "brave/common/extensions/api/brave_theme.h"
 
-namespace extensions {
-namespace api {
+namespace extensions::api {
 
 ExtensionFunction::ResponseAction BraveThemeGetBraveThemeListFunction::Run() {
   std::string json_string;
@@ -40,5 +39,4 @@ ExtensionFunction::ResponseAction BraveThemeSetBraveThemeTypeFunction::Run() {
   return RespondNow(NoArguments());
 }
 
-}  // namespace api
-}  // namespace extensions
+}  // namespace extensions::api
diff --git a/browser/extensions/api/brave_wallet_api.cc b/browser/extensions/api/brave_wallet_api.cc
index f2a524c17d4..45a77251cec 100644
--- a/browser/extensions/api/brave_wallet_api.cc
+++ b/browser/extensions/api/brave_wallet_api.cc
@@ -52,8 +52,7 @@ base::Value::Dict MakeSelectValue(const std::u16string& name,
 
 }  // namespace
 
-namespace extensions {
-namespace api {
+namespace extensions::api {
 
 ExtensionFunction::ResponseAction BraveWalletReadyFunction::Run() {
   if (browser_context()->IsTor()) {
@@ -195,5 +194,4 @@ BraveWalletIsNativeWalletEnabledFunction::Run() {
   return RespondNow(WithArguments(::brave_wallet::IsNativeWalletEnabled()));
 }
 
-}  // namespace api
-}  // namespace extensions
+}  // namespace extensions::api
diff --git a/browser/extensions/api/greaselion_api.cc b/browser/extensions/api/greaselion_api.cc
index 416afe6259c..075357cb827 100644
--- a/browser/extensions/api/greaselion_api.cc
+++ b/browser/extensions/api/greaselion_api.cc
@@ -14,8 +14,7 @@
 #include "brave/components/greaselion/browser/greaselion_service.h"
 #include "chrome/browser/profiles/profile.h"
 
-namespace extensions {
-namespace api {
+namespace extensions::api {
 
 ExtensionFunction::ResponseAction
 GreaselionIsGreaselionExtensionFunction::Run() {
@@ -34,5 +33,4 @@ GreaselionIsGreaselionExtensionFunction::Run() {
   return RespondNow(WithArguments(result));
 }
 
-}  // namespace api
-}  // namespace extensions
+}  // namespace extensions::api
diff --git a/browser/extensions/api/ipfs_api.cc b/browser/extensions/api/ipfs_api.cc
index 9e450a35ce2..c52dee71fa6 100644
--- a/browser/extensions/api/ipfs_api.cc
+++ b/browser/extensions/api/ipfs_api.cc
@@ -87,8 +87,7 @@ bool WriteFileOnFileThread(const base::FilePath& path,
 
 }  // namespace
 
-namespace extensions {
-namespace api {
+namespace extensions::api {
 
 ExtensionFunction::ResponseAction IpfsRemoveIpfsPeerFunction::Run() {
   if (!::ipfs::IpfsServiceFactory::IsIpfsEnabled(browser_context()))
@@ -610,5 +609,4 @@ ExtensionFunction::ResponseAction IpfsSetGatewayFallbackEnabledFunction::Run() {
   return RespondNow(WithArguments(true));
 }
 
-}  // namespace api
-}  // namespace extensions
+}  // namespace extensions::api
diff --git a/browser/extensions/api/rewards_notifications_api.cc b/browser/extensions/api/rewards_notifications_api.cc
index bba57e2cd0e..b478862f98d 100644
--- a/browser/extensions/api/rewards_notifications_api.cc
+++ b/browser/extensions/api/rewards_notifications_api.cc
@@ -17,8 +17,7 @@
 using brave_rewards::RewardsNotificationService;
 using brave_rewards::RewardsServiceFactory;
 
-namespace extensions {
-namespace api {
+namespace extensions::api {
 
 RewardsNotificationsAddNotificationFunction::
     ~RewardsNotificationsAddNotificationFunction() = default;
@@ -102,5 +101,4 @@ RewardsNotificationsGetAllNotificationsFunction::Run() {
   return RespondNow(NoArguments());
 }
 
-}  // namespace api
-}  // namespace extensions
+}  // namespace extensions::api
diff --git a/browser/themes/brave_dark_mode_utils_internal.cc b/browser/themes/brave_dark_mode_utils_internal.cc
index cca4a2d16c0..d8e5a685db3 100644
--- a/browser/themes/brave_dark_mode_utils_internal.cc
+++ b/browser/themes/brave_dark_mode_utils_internal.cc
@@ -30,9 +30,7 @@ void ReCalcAndSetPreferredColorScheme() {
 
 }  // namespace ui
 
-namespace dark_mode {
-
-namespace internal {
+namespace dark_mode::internal {
 
 void SetSystemDarkModeForNonDefaultMode(bool dark_mode) {
   // Call SetUseDarkColors() first then call ReCalcPreferredColorScheme()
@@ -47,6 +45,4 @@ void SetSystemDarkModeForNonDefaultMode(bool dark_mode) {
   ui::NativeTheme::GetInstanceForWeb()->NotifyOnNativeThemeUpdated();
 }
 
-}  // namespace internal
-
-}  // namespace dark_mode
+}  // namespace dark_mode::internal
diff --git a/chromium_src/brave/third_party/bitcoin-core/src/src/serialize.h b/chromium_src/brave/third_party/bitcoin-core/src/src/serialize.h
index e9380379de5..9129b76eb9b 100644
--- a/chromium_src/brave/third_party/bitcoin-core/src/src/serialize.h
+++ b/chromium_src/brave/third_party/bitcoin-core/src/src/serialize.h
@@ -13,11 +13,9 @@
 
 #include "base/check.h"
 
-namespace std {
-namespace brave {
+namespace std::brave {
 using string = ::std::string;
 }
-}  // namespace std
 
 #define throw CHECK(false) <<
 #define ios_base brave
diff --git a/components/brave_federated/features.cc b/components/brave_federated/features.cc
index be6f4db385f..97b977a76c1 100644
--- a/components/brave_federated/features.cc
+++ b/components/brave_federated/features.cc
@@ -8,8 +8,7 @@
 #include "base/metrics/field_trial_params.h"
 #include "base/time/time.h"
 
-namespace brave_federated {
-namespace features {
+namespace brave_federated::features {
 
 namespace {
 
@@ -87,5 +86,4 @@ bool MockCollectionRequests() {
       kDefaultMockCollectionRequests);
 }
 
-}  // namespace features
-}  // namespace brave_federated
+}  // namespace brave_federated::features
diff --git a/components/brave_page_graph/common/features.cc b/components/brave_page_graph/common/features.cc
index 82349bbe143..58104c59612 100644
--- a/components/brave_page_graph/common/features.cc
+++ b/components/brave_page_graph/common/features.cc
@@ -5,13 +5,11 @@
 
 #include "brave/components/brave_page_graph/common/features.h"
 
-namespace brave_page_graph {
-namespace features {
+namespace brave_page_graph::features {
 
 // Enables PageGraph machinery to generate GraphML representation of web pages
 // construction order. Under the hood this enables PageGraph blink CoreProbes
 // agent and activates some DevTools APIs to interact with the PageGraph engine.
 BASE_FEATURE(kPageGraph, "PageGraph", base::FEATURE_DISABLED_BY_DEFAULT);
 
-}  // namespace features
-}  // namespace brave_page_graph
+}  // namespace brave_page_graph::features
diff --git a/components/brave_rewards/browser/rewards_p3a.cc b/components/brave_rewards/browser/rewards_p3a.cc
index 0da3f2a9afa..c907f0a44d4 100644
--- a/components/brave_rewards/browser/rewards_p3a.cc
+++ b/components/brave_rewards/browser/rewards_p3a.cc
@@ -14,8 +14,7 @@
 #include "brave/components/time_period_storage/monthly_storage.h"
 #include "components/prefs/pref_service.h"
 
-namespace brave_rewards {
-namespace p3a {
+namespace brave_rewards::p3a {
 
 namespace {
 
@@ -177,5 +176,4 @@ void ConversionMonitor::ReportPanelTriggerCount() {
                                      kPanelCountBuckets, total);
 }
 
-}  // namespace p3a
-}  // namespace brave_rewards
+}  // namespace brave_rewards::p3a
diff --git a/components/brave_rewards/core/common/brotli_util.cc b/components/brave_rewards/core/common/brotli_util.cc
index 9fb0397499c..943040cea38 100644
--- a/components/brave_rewards/core/common/brotli_util.cc
+++ b/components/brave_rewards/core/common/brotli_util.cc
@@ -74,8 +74,7 @@ class BrotliStreamDecoder {
 
 }  // namespace
 
-namespace brave_rewards::internal {
-namespace util {
+namespace brave_rewards::internal::util {
 
 bool DecodeBrotliString(std::string_view input,
                         size_t uncompressed_size,
@@ -113,5 +112,4 @@ bool DecodeBrotliStringWithBuffer(std::string_view input,
   return result == BrotliStreamDecoder::Result::Done;
 }
 
-}  // namespace util
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::util
diff --git a/components/brave_rewards/core/common/brotli_util_unittest.cc b/components/brave_rewards/core/common/brotli_util_unittest.cc
index 289d25bfb65..64a469d19c1 100644
--- a/components/brave_rewards/core/common/brotli_util_unittest.cc
+++ b/components/brave_rewards/core/common/brotli_util_unittest.cc
@@ -27,8 +27,7 @@ constexpr char kUncompressed[] =
 
 }  // namespace
 
-namespace brave_rewards::internal {
-namespace util {
+namespace brave_rewards::internal::util {
 
 class RewardsBrotliHelpersTest : public testing::Test {
  protected:
@@ -70,5 +69,4 @@ TEST_F(RewardsBrotliHelpersTest, TestDecodeWithBuffer) {
   EXPECT_FALSE(DecodeBrotliStringWithBuffer("not brotli", 16, &s));
 }
 
-}  // namespace util
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::util
diff --git a/components/brave_rewards/core/common/random_util.cc b/components/brave_rewards/core/common/random_util.cc
index 97c72248c1a..0c5fa7c73f3 100644
--- a/components/brave_rewards/core/common/random_util.cc
+++ b/components/brave_rewards/core/common/random_util.cc
@@ -27,8 +27,7 @@ std::string EncodeStringForPKCE(const std::string& data) {
 
 }  // namespace
 
-namespace brave_rewards::internal {
-namespace util {
+namespace brave_rewards::internal::util {
 
 std::string GenerateRandomHexString() {
   const size_t kLength = 32;
@@ -45,5 +44,4 @@ std::string GeneratePKCECodeChallenge(const std::string& code_verifier) {
   return EncodeStringForPKCE(crypto::SHA256HashString(code_verifier));
 }
 
-}  // namespace util
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::util
diff --git a/components/brave_rewards/core/common/time_util.cc b/components/brave_rewards/core/common/time_util.cc
index 535e3a57e49..d4dc45da299 100644
--- a/components/brave_rewards/core/common/time_util.cc
+++ b/components/brave_rewards/core/common/time_util.cc
@@ -8,8 +8,7 @@
 #include <algorithm>
 #include "brave_base/random.h"
 
-namespace brave_rewards::internal {
-namespace util {
+namespace brave_rewards::internal::util {
 
 mojom::ActivityMonth GetCurrentMonth() {
   base::Time now = base::Time::Now();
@@ -49,5 +48,4 @@ base::TimeDelta GetRandomizedDelayWithBackoff(base::TimeDelta delay,
   return GetRandomizedDelay(std::min(delay, max_delay));
 }
 
-}  // namespace util
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::util
diff --git a/components/brave_rewards/core/contribution/contribution_monthly.cc b/components/brave_rewards/core/contribution/contribution_monthly.cc
index 21bba654d72..6e4d7776b26 100644
--- a/components/brave_rewards/core/contribution/contribution_monthly.cc
+++ b/components/brave_rewards/core/contribution/contribution_monthly.cc
@@ -17,8 +17,7 @@
 #include "brave/components/brave_rewards/core/database/database.h"
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 
-namespace brave_rewards::internal {
-namespace contribution {
+namespace brave_rewards::internal::contribution {
 
 ContributionMonthly::ContributionMonthly(RewardsEngine& engine)
     : engine_(engine) {}
@@ -104,5 +103,4 @@ void ContributionMonthly::OnNextContributionDateAdvanced(
   std::move(callback).Run(mojom::Result::OK);
 }
 
-}  // namespace contribution
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::contribution
diff --git a/components/brave_rewards/core/contribution/contribution_util.cc b/components/brave_rewards/core/contribution/contribution_util.cc
index 24531a3e563..95f803c5b55 100644
--- a/components/brave_rewards/core/contribution/contribution_util.cc
+++ b/components/brave_rewards/core/contribution/contribution_util.cc
@@ -9,8 +9,7 @@
 #include "brave/components/brave_rewards/core/contribution/contribution_util.h"
 #include "brave/components/brave_rewards/core/global_constants.h"
 
-namespace brave_rewards::internal {
-namespace contribution {
+namespace brave_rewards::internal::contribution {
 
 mojom::ReportType GetReportTypeFromRewardsType(const mojom::RewardsType type) {
   switch (static_cast<int>(type)) {
@@ -100,5 +99,4 @@ int32_t GetVotesFromAmount(const double amount) {
   return std::floor(amount / constant::kVotePrice);
 }
 
-}  // namespace contribution
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::contribution
diff --git a/components/brave_rewards/core/contribution/contribution_util_unittest.cc b/components/brave_rewards/core/contribution/contribution_util_unittest.cc
index 27cdb1d77b6..31019f77439 100644
--- a/components/brave_rewards/core/contribution/contribution_util_unittest.cc
+++ b/components/brave_rewards/core/contribution/contribution_util_unittest.cc
@@ -8,8 +8,7 @@
 #include "brave/components/brave_rewards/core/global_constants.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
-namespace brave_rewards::internal {
-namespace contribution {
+namespace brave_rewards::internal::contribution {
 
 class RewardsContributionUtilTest : public testing::Test {};
 
@@ -61,5 +60,4 @@ TEST(RewardsContributionUtilTest, HaveEnoughFundsToContribute) {
   ASSERT_TRUE(HaveEnoughFundsToContribute(&amount, false, balance));
 }
 
-}  // namespace contribution
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::contribution
diff --git a/components/brave_rewards/core/credentials/credentials_common.cc b/components/brave_rewards/core/credentials/credentials_common.cc
index 2020b083588..0c51a55bd38 100644
--- a/components/brave_rewards/core/credentials/credentials_common.cc
+++ b/components/brave_rewards/core/credentials/credentials_common.cc
@@ -14,8 +14,7 @@
 #include "brave/components/brave_rewards/core/database/database.h"
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 
-namespace brave_rewards::internal {
-namespace credential {
+namespace brave_rewards::internal::credential {
 
 CredentialsCommon::CredentialsCommon(RewardsEngine& engine) : engine_(engine) {}
 
@@ -107,5 +106,4 @@ void CredentialsCommon::OnSaveUnblindedCreds(ResultCallback callback,
                                               std::move(callback));
 }
 
-}  // namespace credential
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::credential
diff --git a/components/brave_rewards/core/credentials/credentials_redeem.cc b/components/brave_rewards/core/credentials/credentials_redeem.cc
index a75bce71ec5..2032829037c 100644
--- a/components/brave_rewards/core/credentials/credentials_redeem.cc
+++ b/components/brave_rewards/core/credentials/credentials_redeem.cc
@@ -5,8 +5,7 @@
 
 #include "brave/components/brave_rewards/core/credentials/credentials_redeem.h"
 
-namespace brave_rewards::internal {
-namespace credential {
+namespace brave_rewards::internal::credential {
 
 CredentialsRedeem::CredentialsRedeem() = default;
 
@@ -14,5 +13,4 @@ CredentialsRedeem::CredentialsRedeem(const CredentialsRedeem& info) = default;
 
 CredentialsRedeem::~CredentialsRedeem() = default;
 
-}  // namespace credential
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::credential
diff --git a/components/brave_rewards/core/credentials/credentials_trigger.cc b/components/brave_rewards/core/credentials/credentials_trigger.cc
index 5f143ff915c..e57275e5c4c 100644
--- a/components/brave_rewards/core/credentials/credentials_trigger.cc
+++ b/components/brave_rewards/core/credentials/credentials_trigger.cc
@@ -5,8 +5,7 @@
 
 #include "brave/components/brave_rewards/core/credentials/credentials_trigger.h"
 
-namespace brave_rewards::internal {
-namespace credential {
+namespace brave_rewards::internal::credential {
 
 CredentialsTrigger::CredentialsTrigger() = default;
 
@@ -15,5 +14,4 @@ CredentialsTrigger::CredentialsTrigger(const CredentialsTrigger& info) =
 
 CredentialsTrigger::~CredentialsTrigger() = default;
 
-}  // namespace credential
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::credential
diff --git a/components/brave_rewards/core/credentials/credentials_util.cc b/components/brave_rewards/core/credentials/credentials_util.cc
index 6e17ed09a42..0d38aa6cc89 100644
--- a/components/brave_rewards/core/credentials/credentials_util.cc
+++ b/components/brave_rewards/core/credentials/credentials_util.cc
@@ -19,8 +19,7 @@
 #include "brave/components/challenge_bypass_ristretto/verification_key.h"
 #include "brave/components/challenge_bypass_ristretto/verification_signature.h"
 
-namespace brave_rewards::internal {
-namespace credential {
+namespace brave_rewards::internal::credential {
 
 using challenge_bypass_ristretto::BatchDLEQProof;
 using challenge_bypass_ristretto::PublicKey;
@@ -248,5 +247,4 @@ base::Value::Dict GenerateSuggestionMock(const std::string& token_value,
   return dict;
 }
 
-}  // namespace credential
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::credential
diff --git a/components/brave_rewards/core/credentials/credentials_util_unittest.cc b/components/brave_rewards/core/credentials/credentials_util_unittest.cc
index 6a92ee03280..47d5627d826 100644
--- a/components/brave_rewards/core/credentials/credentials_util_unittest.cc
+++ b/components/brave_rewards/core/credentials/credentials_util_unittest.cc
@@ -12,8 +12,7 @@
 #include "brave/components/brave_rewards/core/rewards_callbacks.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
-namespace brave_rewards::internal {
-namespace credential {
+namespace brave_rewards::internal::credential {
 
 class RewardsPromotionUtilTest : public testing::Test {
  public:
@@ -116,5 +115,4 @@ TEST_F(RewardsPromotionUtilTest, UnBlindCredsCredsNotCorrect) {
             "Failed to verify and unblind batch DLEQ proof");
 }
 
-}  // namespace credential
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::credential
diff --git a/components/brave_rewards/core/database/database.cc b/components/brave_rewards/core/database/database.cc
index 5ffd816e019..d39da6743aa 100644
--- a/components/brave_rewards/core/database/database.cc
+++ b/components/brave_rewards/core/database/database.cc
@@ -12,8 +12,7 @@
 #include "brave/components/brave_rewards/core/logging/event_log_keys.h"
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 
-namespace brave_rewards::internal {
-namespace database {
+namespace brave_rewards::internal::database {
 
 Database::Database(RewardsEngine& engine)
     : engine_(engine),
@@ -486,5 +485,4 @@ void Database::GetSpendableUnblindedTokensByBatchTypes(
                                                       std::move(callback));
 }
 
-}  // namespace database
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::database
diff --git a/components/brave_rewards/core/database/database_contribution_info.cc b/components/brave_rewards/core/database/database_contribution_info.cc
index c2fa00cc919..7474e2e963d 100644
--- a/components/brave_rewards/core/database/database_contribution_info.cc
+++ b/components/brave_rewards/core/database/database_contribution_info.cc
@@ -14,8 +14,7 @@
 #include "brave/components/brave_rewards/core/database/database_util.h"
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 
-namespace brave_rewards::internal {
-namespace database {
+namespace brave_rewards::internal::database {
 
 namespace {
 
@@ -474,5 +473,4 @@ void DatabaseContributionInfo::FinishAllInProgressRecords(
       base::BindOnce(&OnResultCallback, std::move(callback)));
 }
 
-}  // namespace database
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::database
diff --git a/components/brave_rewards/core/database/database_contribution_info_publishers.cc b/components/brave_rewards/core/database/database_contribution_info_publishers.cc
index b8b35b60ed5..195ddb28e75 100644
--- a/components/brave_rewards/core/database/database_contribution_info_publishers.cc
+++ b/components/brave_rewards/core/database/database_contribution_info_publishers.cc
@@ -11,8 +11,7 @@
 #include "brave/components/brave_rewards/core/database/database_util.h"
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 
-namespace brave_rewards::internal {
-namespace database {
+namespace brave_rewards::internal::database {
 
 namespace {
 
@@ -227,5 +226,4 @@ void DatabaseContributionInfoPublishers::UpdateContributedAmount(
       base::BindOnce(&OnResultCallback, std::move(callback)));
 }
 
-}  // namespace database
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::database
diff --git a/components/brave_rewards/core/database/database_contribution_queue.cc b/components/brave_rewards/core/database/database_contribution_queue.cc
index 3fb716fe264..16f3b8b43f2 100644
--- a/components/brave_rewards/core/database/database_contribution_queue.cc
+++ b/components/brave_rewards/core/database/database_contribution_queue.cc
@@ -13,8 +13,7 @@
 #include "brave/components/brave_rewards/core/database/database_util.h"
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 
-namespace brave_rewards::internal {
-namespace database {
+namespace brave_rewards::internal::database {
 
 namespace {
 
@@ -182,5 +181,4 @@ void DatabaseContributionQueue::MarkRecordAsComplete(const std::string& id,
       base::BindOnce(&OnResultCallback, std::move(callback)));
 }
 
-}  // namespace database
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::database
diff --git a/components/brave_rewards/core/database/database_contribution_queue_publishers.cc b/components/brave_rewards/core/database/database_contribution_queue_publishers.cc
index 34a8fffc75a..27c11b3e556 100644
--- a/components/brave_rewards/core/database/database_contribution_queue_publishers.cc
+++ b/components/brave_rewards/core/database/database_contribution_queue_publishers.cc
@@ -12,8 +12,7 @@
 #include "brave/components/brave_rewards/core/database/database_util.h"
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 
-namespace brave_rewards::internal {
-namespace database {
+namespace brave_rewards::internal::database {
 
 namespace {
 
@@ -120,5 +119,4 @@ void DatabaseContributionQueuePublishers::OnGetRecordsByQueueId(
   std::move(callback).Run(std::move(list));
 }
 
-}  // namespace database
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::database
diff --git a/components/brave_rewards/core/database/database_creds_batch.cc b/components/brave_rewards/core/database/database_creds_batch.cc
index 9032e256063..06bf11e281d 100644
--- a/components/brave_rewards/core/database/database_creds_batch.cc
+++ b/components/brave_rewards/core/database/database_creds_batch.cc
@@ -10,8 +10,7 @@
 #include "brave/components/brave_rewards/core/database/database_util.h"
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 
-namespace brave_rewards::internal {
-namespace database {
+namespace brave_rewards::internal::database {
 
 namespace {
 
@@ -324,5 +323,4 @@ void DatabaseCredsBatch::GetRecordsByTriggers(
                      std::move(callback)));
 }
 
-}  // namespace database
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::database
diff --git a/components/brave_rewards/core/database/database_event_log.cc b/components/brave_rewards/core/database/database_event_log.cc
index 9dc5cfa450a..496079a4ba9 100644
--- a/components/brave_rewards/core/database/database_event_log.cc
+++ b/components/brave_rewards/core/database/database_event_log.cc
@@ -14,8 +14,7 @@
 #include "brave/components/brave_rewards/core/database/database_util.h"
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 
-namespace brave_rewards::internal {
-namespace database {
+namespace brave_rewards::internal::database {
 
 namespace {
 
@@ -146,5 +145,4 @@ void DatabaseEventLog::OnGetAllRecords(GetEventLogsCallback callback,
   std::move(callback).Run(std::move(list));
 }
 
-}  // namespace database
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::database
diff --git a/components/brave_rewards/core/database/database_initialize.cc b/components/brave_rewards/core/database/database_initialize.cc
index e5d8242e1a9..211eee21c3c 100644
--- a/components/brave_rewards/core/database/database_initialize.cc
+++ b/components/brave_rewards/core/database/database_initialize.cc
@@ -10,8 +10,7 @@
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 #include "brave/components/brave_rewards/core/state/state_keys.h"
 
-namespace brave_rewards::internal {
-namespace database {
+namespace brave_rewards::internal::database {
 
 DatabaseInitialize::DatabaseInitialize(RewardsEngine& engine)
     : engine_(engine), migration_(engine) {}
@@ -50,5 +49,4 @@ void DatabaseInitialize::OnInitialize(ResultCallback callback,
   migration_.Start(current_table_version, std::move(callback));
 }
 
-}  // namespace database
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::database
diff --git a/components/brave_rewards/core/database/database_media_publisher_info.cc b/components/brave_rewards/core/database/database_media_publisher_info.cc
index b816209b21d..a954c07661e 100644
--- a/components/brave_rewards/core/database/database_media_publisher_info.cc
+++ b/components/brave_rewards/core/database/database_media_publisher_info.cc
@@ -11,8 +11,7 @@
 #include "brave/components/brave_rewards/core/database/database_util.h"
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 
-namespace brave_rewards::internal {
-namespace database {
+namespace brave_rewards::internal::database {
 
 namespace {
 
@@ -131,5 +130,4 @@ void DatabaseMediaPublisherInfo::OnGetRecord(
   std::move(callback).Run(mojom::Result::OK, std::move(info));
 }
 
-}  // namespace database
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::database
diff --git a/components/brave_rewards/core/database/database_migration.cc b/components/brave_rewards/core/database/database_migration.cc
index 7afd459c66c..90043c01e9e 100644
--- a/components/brave_rewards/core/database/database_migration.cc
+++ b/components/brave_rewards/core/database/database_migration.cc
@@ -61,8 +61,7 @@
 // you should keep old table with name unblinded_tokens_29
 // Reference: https://github.com/brave/brave-browser/issues/10784
 
-namespace brave_rewards::internal {
-namespace database {
+namespace brave_rewards::internal::database {
 
 uint32_t DatabaseMigration::test_target_version_ = 0;
 
@@ -209,5 +208,4 @@ void DatabaseMigration::RunDBTransactionCallback(
   std::move(callback).Run(mojom::Result::FAILED);
 }
 
-}  // namespace database
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::database
diff --git a/components/brave_rewards/core/database/database_mock.cc b/components/brave_rewards/core/database/database_mock.cc
index decc92ff216..eca32e71577 100644
--- a/components/brave_rewards/core/database/database_mock.cc
+++ b/components/brave_rewards/core/database/database_mock.cc
@@ -5,12 +5,10 @@
 
 #include "brave/components/brave_rewards/core/database/database_mock.h"
 
-namespace brave_rewards::internal {
-namespace database {
+namespace brave_rewards::internal::database {
 
 MockDatabase::MockDatabase(RewardsEngine& engine) : Database(engine) {}
 
 MockDatabase::~MockDatabase() = default;
 
-}  // namespace database
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::database
diff --git a/components/brave_rewards/core/database/database_publisher_info.cc b/components/brave_rewards/core/database/database_publisher_info.cc
index f40721ceacf..e29f0940e1b 100644
--- a/components/brave_rewards/core/database/database_publisher_info.cc
+++ b/components/brave_rewards/core/database/database_publisher_info.cc
@@ -21,8 +21,7 @@ const char kTableName[] = "publisher_info";
 
 }  // namespace
 
-namespace brave_rewards::internal {
-namespace database {
+namespace brave_rewards::internal::database {
 
 DatabasePublisherInfo::DatabasePublisherInfo(RewardsEngine& engine)
     : DatabaseTable(engine) {}
@@ -330,5 +329,4 @@ void DatabasePublisherInfo::OnGetExcludedList(
   std::move(callback).Run(std::move(list));
 }
 
-}  // namespace database
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::database
diff --git a/components/brave_rewards/core/database/database_recurring_tip.cc b/components/brave_rewards/core/database/database_recurring_tip.cc
index 17759dbee4c..68ef8c83765 100644
--- a/components/brave_rewards/core/database/database_recurring_tip.cc
+++ b/components/brave_rewards/core/database/database_recurring_tip.cc
@@ -17,8 +17,7 @@
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 #include "brave/components/brave_rewards/core/state/state.h"
 
-namespace brave_rewards::internal {
-namespace database {
+namespace brave_rewards::internal::database {
 
 namespace {
 
@@ -292,5 +291,4 @@ void DatabaseRecurringTip::DeleteRecord(const std::string& publisher_key,
       base::BindOnce(&OnResultCallback, std::move(callback)));
 }
 
-}  // namespace database
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::database
diff --git a/components/brave_rewards/core/database/database_server_publisher_banner.cc b/components/brave_rewards/core/database/database_server_publisher_banner.cc
index 95bb98ec881..3b05048b60d 100644
--- a/components/brave_rewards/core/database/database_server_publisher_banner.cc
+++ b/components/brave_rewards/core/database/database_server_publisher_banner.cc
@@ -16,8 +16,7 @@ const char kTableName[] = "server_publisher_banner";
 
 }  // namespace
 
-namespace brave_rewards::internal {
-namespace database {
+namespace brave_rewards::internal::database {
 
 DatabaseServerPublisherBanner::DatabaseServerPublisherBanner(
     RewardsEngine& engine)
@@ -166,5 +165,4 @@ void DatabaseServerPublisherBanner::OnGetRecordLinks(
   std::move(callback).Run(std::move(banner_pointer));
 }
 
-}  // namespace database
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::database
diff --git a/components/brave_rewards/core/database/database_server_publisher_info.cc b/components/brave_rewards/core/database/database_server_publisher_info.cc
index a7c1c10304b..7927fd0947a 100644
--- a/components/brave_rewards/core/database/database_server_publisher_info.cc
+++ b/components/brave_rewards/core/database/database_server_publisher_info.cc
@@ -17,9 +17,7 @@ const char kTableName[] = "server_publisher_info";
 
 }  // namespace
 
-namespace brave_rewards::internal {
-
-namespace database {
+namespace brave_rewards::internal::database {
 
 DatabaseServerPublisherInfo::DatabaseServerPublisherInfo(RewardsEngine& engine)
     : DatabaseTable(engine), banner_(engine) {}
@@ -205,5 +203,4 @@ void DatabaseServerPublisherInfo::OnExpiredRecordsSelected(
       base::BindOnce(&OnResultCallback, std::move(callback)));
 }
 
-}  // namespace database
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::database
diff --git a/components/brave_rewards/core/database/database_server_publisher_links.cc b/components/brave_rewards/core/database/database_server_publisher_links.cc
index 62fb66915b3..10c3f7c62be 100644
--- a/components/brave_rewards/core/database/database_server_publisher_links.cc
+++ b/components/brave_rewards/core/database/database_server_publisher_links.cc
@@ -16,8 +16,7 @@ const char kTableName[] = "server_publisher_links";
 
 }  // namespace
 
-namespace brave_rewards::internal {
-namespace database {
+namespace brave_rewards::internal::database {
 
 DatabaseServerPublisherLinks::DatabaseServerPublisherLinks(
     RewardsEngine& engine)
@@ -122,5 +121,4 @@ void DatabaseServerPublisherLinks::OnGetRecord(
   std::move(callback).Run(links);
 }
 
-}  // namespace database
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::database
diff --git a/components/brave_rewards/core/database/database_sku_order.cc b/components/brave_rewards/core/database/database_sku_order.cc
index 70d62b6b6c6..cfc9e8b086d 100644
--- a/components/brave_rewards/core/database/database_sku_order.cc
+++ b/components/brave_rewards/core/database/database_sku_order.cc
@@ -11,8 +11,7 @@
 #include "brave/components/brave_rewards/core/database/database_util.h"
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 
-namespace brave_rewards::internal {
-namespace database {
+namespace brave_rewards::internal::database {
 
 namespace {
 
@@ -240,5 +239,4 @@ void DatabaseSKUOrder::SaveContributionIdForSKUOrder(
       base::BindOnce(&OnResultCallback, std::move(callback)));
 }
 
-}  // namespace database
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::database
diff --git a/components/brave_rewards/core/database/database_sku_order_items.cc b/components/brave_rewards/core/database/database_sku_order_items.cc
index 1486a139bd5..c19deb292e2 100644
--- a/components/brave_rewards/core/database/database_sku_order_items.cc
+++ b/components/brave_rewards/core/database/database_sku_order_items.cc
@@ -11,8 +11,7 @@
 #include "brave/components/brave_rewards/core/database/database_util.h"
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 
-namespace brave_rewards::internal {
-namespace database {
+namespace brave_rewards::internal::database {
 
 namespace {
 
@@ -133,5 +132,4 @@ void DatabaseSKUOrderItems::OnGetRecordsByOrderId(
   std::move(callback).Run(std::move(list));
 }
 
-}  // namespace database
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::database
diff --git a/components/brave_rewards/core/database/database_sku_transaction.cc b/components/brave_rewards/core/database/database_sku_transaction.cc
index 0c6f06671d1..8bc853bb091 100644
--- a/components/brave_rewards/core/database/database_sku_transaction.cc
+++ b/components/brave_rewards/core/database/database_sku_transaction.cc
@@ -11,8 +11,7 @@
 #include "brave/components/brave_rewards/core/database/database_util.h"
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 
-namespace brave_rewards::internal {
-namespace database {
+namespace brave_rewards::internal::database {
 
 namespace {
 
@@ -169,5 +168,4 @@ void DatabaseSKUTransaction::OnGetRecord(GetSKUTransactionCallback callback,
   std::move(callback).Run(std::move(info));
 }
 
-}  // namespace database
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::database
diff --git a/components/brave_rewards/core/database/database_table.cc b/components/brave_rewards/core/database/database_table.cc
index 354a7dc0d7c..aa8549cee77 100644
--- a/components/brave_rewards/core/database/database_table.cc
+++ b/components/brave_rewards/core/database/database_table.cc
@@ -6,12 +6,10 @@
 #include "brave/components/brave_rewards/core/database/database_table.h"
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 
-namespace brave_rewards::internal {
-namespace database {
+namespace brave_rewards::internal::database {
 
 DatabaseTable::DatabaseTable(RewardsEngine& engine) : engine_(engine) {}
 
 DatabaseTable::~DatabaseTable() = default;
 
-}  // namespace database
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::database
diff --git a/components/brave_rewards/core/database/database_unblinded_token.cc b/components/brave_rewards/core/database/database_unblinded_token.cc
index e1c083a8899..8f78b5a860a 100644
--- a/components/brave_rewards/core/database/database_unblinded_token.cc
+++ b/components/brave_rewards/core/database/database_unblinded_token.cc
@@ -15,8 +15,7 @@
 #include "brave/components/brave_rewards/core/database/database_util.h"
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 
-namespace brave_rewards::internal {
-namespace database {
+namespace brave_rewards::internal::database {
 
 namespace {
 
@@ -364,5 +363,4 @@ void DatabaseUnblindedToken::GetSpendableRecordListByBatchTypes(
                      base::Unretained(this), std::move(callback)));
 }
 
-}  // namespace database
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::database
diff --git a/components/brave_rewards/core/database/database_util.cc b/components/brave_rewards/core/database/database_util.cc
index 163dc76a6bb..9b66e174e66 100644
--- a/components/brave_rewards/core/database/database_util.cc
+++ b/components/brave_rewards/core/database/database_util.cc
@@ -16,8 +16,7 @@ const int kCompatibleVersionNumber = 1;
 
 }  // namespace
 
-namespace brave_rewards::internal {
-namespace database {
+namespace brave_rewards::internal::database {
 
 void BindNull(mojom::DBCommand* command, const int index) {
   if (!command) {
@@ -185,5 +184,4 @@ std::string GenerateStringInCase(const std::vector<std::string>& items) {
   return base::StringPrintf("'%s'", items_join.c_str());
 }
 
-}  // namespace database
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::database
diff --git a/components/brave_rewards/core/endpoint/bitflyer/bitflyer_server.cc b/components/brave_rewards/core/endpoint/bitflyer/bitflyer_server.cc
index e7406b2eb87..e39fefb2ab4 100644
--- a/components/brave_rewards/core/endpoint/bitflyer/bitflyer_server.cc
+++ b/components/brave_rewards/core/endpoint/bitflyer/bitflyer_server.cc
@@ -7,13 +7,11 @@
 
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 
-namespace brave_rewards::internal {
-namespace endpoint {
+namespace brave_rewards::internal::endpoint {
 
 BitflyerServer::BitflyerServer(RewardsEngine& engine)
     : get_balance_(engine), post_oauth_(engine) {}
 
 BitflyerServer::~BitflyerServer() = default;
 
-}  // namespace endpoint
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::endpoint
diff --git a/components/brave_rewards/core/endpoint/bitflyer/get_balance/get_balance_bitflyer.cc b/components/brave_rewards/core/endpoint/bitflyer/get_balance/get_balance_bitflyer.cc
index a9fc8f4beb8..63b22de52ea 100644
--- a/components/brave_rewards/core/endpoint/bitflyer/get_balance/get_balance_bitflyer.cc
+++ b/components/brave_rewards/core/endpoint/bitflyer/get_balance/get_balance_bitflyer.cc
@@ -15,9 +15,7 @@
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 #include "net/http/http_status_code.h"
 
-namespace brave_rewards::internal {
-namespace endpoint {
-namespace bitflyer {
+namespace brave_rewards::internal::endpoint::bitflyer {
 
 GetBalance::GetBalance(RewardsEngine& engine) : engine_(engine) {}
 
@@ -119,6 +117,4 @@ void GetBalance::OnRequest(GetBalanceCallback callback,
   std::move(callback).Run(result, available);
 }
 
-}  // namespace bitflyer
-}  // namespace endpoint
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::endpoint::bitflyer
diff --git a/components/brave_rewards/core/endpoint/gemini/gemini_server.cc b/components/brave_rewards/core/endpoint/gemini/gemini_server.cc
index d495ffca1bb..20ba752c03f 100644
--- a/components/brave_rewards/core/endpoint/gemini/gemini_server.cc
+++ b/components/brave_rewards/core/endpoint/gemini/gemini_server.cc
@@ -7,8 +7,7 @@
 
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 
-namespace brave_rewards::internal {
-namespace endpoint {
+namespace brave_rewards::internal::endpoint {
 
 GeminiServer::GeminiServer(RewardsEngine& engine)
     : post_account_(engine),
@@ -18,5 +17,4 @@ GeminiServer::GeminiServer(RewardsEngine& engine)
 
 GeminiServer::~GeminiServer() = default;
 
-}  // namespace endpoint
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::endpoint
diff --git a/components/brave_rewards/core/endpoint/gemini/post_balance/post_balance_gemini.cc b/components/brave_rewards/core/endpoint/gemini/post_balance/post_balance_gemini.cc
index a4d6fe57f55..8097ec9213a 100644
--- a/components/brave_rewards/core/endpoint/gemini/post_balance/post_balance_gemini.cc
+++ b/components/brave_rewards/core/endpoint/gemini/post_balance/post_balance_gemini.cc
@@ -16,9 +16,7 @@
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 #include "net/http/http_status_code.h"
 
-namespace brave_rewards::internal {
-namespace endpoint {
-namespace gemini {
+namespace brave_rewards::internal::endpoint::gemini {
 
 PostBalance::PostBalance(RewardsEngine& engine) : engine_(engine) {}
 
@@ -106,6 +104,4 @@ void PostBalance::OnRequest(PostBalanceCallback callback,
   std::move(callback).Run(result, available);
 }
 
-}  // namespace gemini
-}  // namespace endpoint
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::endpoint::gemini
diff --git a/components/brave_rewards/core/endpoint/payment/get_credentials/get_credentials.cc b/components/brave_rewards/core/endpoint/payment/get_credentials/get_credentials.cc
index 1e84f957e61..797bb5d58e4 100644
--- a/components/brave_rewards/core/endpoint/payment/get_credentials/get_credentials.cc
+++ b/components/brave_rewards/core/endpoint/payment/get_credentials/get_credentials.cc
@@ -16,9 +16,7 @@
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 #include "net/http/http_status_code.h"
 
-namespace brave_rewards::internal {
-namespace endpoint {
-namespace payment {
+namespace brave_rewards::internal::endpoint::payment {
 
 GetCredentials::GetCredentials(RewardsEngine& engine) : engine_(engine) {}
 
@@ -124,6 +122,4 @@ void GetCredentials::OnRequest(GetCredentialsCallback callback,
   std::move(callback).Run(result, std::move(batch));
 }
 
-}  // namespace payment
-}  // namespace endpoint
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::endpoint::payment
diff --git a/components/brave_rewards/core/endpoint/payment/payment_server.cc b/components/brave_rewards/core/endpoint/payment/payment_server.cc
index 37694c53e32..20c55282f45 100644
--- a/components/brave_rewards/core/endpoint/payment/payment_server.cc
+++ b/components/brave_rewards/core/endpoint/payment/payment_server.cc
@@ -7,8 +7,7 @@
 
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 
-namespace brave_rewards::internal {
-namespace endpoint {
+namespace brave_rewards::internal::endpoint {
 
 PaymentServer::PaymentServer(RewardsEngine& engine)
     : post_order_(engine),
@@ -20,5 +19,4 @@ PaymentServer::PaymentServer(RewardsEngine& engine)
 
 PaymentServer::~PaymentServer() = default;
 
-}  // namespace endpoint
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::endpoint
diff --git a/components/brave_rewards/core/endpoint/payment/post_credentials/post_credentials.cc b/components/brave_rewards/core/endpoint/payment/post_credentials/post_credentials.cc
index 5496fccbb24..284c0bbe2e6 100644
--- a/components/brave_rewards/core/endpoint/payment/post_credentials/post_credentials.cc
+++ b/components/brave_rewards/core/endpoint/payment/post_credentials/post_credentials.cc
@@ -14,9 +14,7 @@
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 #include "net/http/http_status_code.h"
 
-namespace brave_rewards::internal {
-namespace endpoint {
-namespace payment {
+namespace brave_rewards::internal::endpoint::payment {
 
 PostCredentials::PostCredentials(RewardsEngine& engine) : engine_(engine) {}
 
@@ -93,6 +91,4 @@ void PostCredentials::OnRequest(PostCredentialsCallback callback,
   std::move(callback).Run(CheckStatusCode(response->status_code));
 }
 
-}  // namespace payment
-}  // namespace endpoint
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::endpoint::payment
diff --git a/components/brave_rewards/core/endpoint/payment/post_order/post_order.cc b/components/brave_rewards/core/endpoint/payment/post_order/post_order.cc
index 128a1b592e1..59cbbbeff91 100644
--- a/components/brave_rewards/core/endpoint/payment/post_order/post_order.cc
+++ b/components/brave_rewards/core/endpoint/payment/post_order/post_order.cc
@@ -16,9 +16,7 @@
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 #include "net/http/http_status_code.h"
 
-namespace brave_rewards::internal {
-namespace endpoint {
-namespace payment {
+namespace brave_rewards::internal::endpoint::payment {
 
 PostOrder::PostOrder(RewardsEngine& engine) : engine_(engine) {}
 
@@ -199,6 +197,4 @@ void PostOrder::OnRequest(std::vector<mojom::SKUOrderItem> items,
   std::move(callback).Run(result, std::move(order));
 }
 
-}  // namespace payment
-}  // namespace endpoint
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::endpoint::payment
diff --git a/components/brave_rewards/core/endpoint/payment/post_transaction_gemini/post_transaction_sku_gemini.cc b/components/brave_rewards/core/endpoint/payment/post_transaction_gemini/post_transaction_sku_gemini.cc
index 7b0c07f761c..43e0e2a44ba 100644
--- a/components/brave_rewards/core/endpoint/payment/post_transaction_gemini/post_transaction_sku_gemini.cc
+++ b/components/brave_rewards/core/endpoint/payment/post_transaction_gemini/post_transaction_sku_gemini.cc
@@ -14,9 +14,7 @@
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 #include "net/http/http_status_code.h"
 
-namespace brave_rewards::internal {
-namespace endpoint {
-namespace payment {
+namespace brave_rewards::internal::endpoint::payment {
 
 PostTransactionGemini::PostTransactionGemini(RewardsEngine& engine)
     : engine_(engine) {}
@@ -99,6 +97,4 @@ void PostTransactionGemini::OnRequest(PostTransactionGeminiCallback callback,
   std::move(callback).Run(CheckStatusCode(response->status_code));
 }
 
-}  // namespace payment
-}  // namespace endpoint
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::endpoint::payment
diff --git a/components/brave_rewards/core/endpoint/payment/post_transaction_uphold/post_transaction_uphold.cc b/components/brave_rewards/core/endpoint/payment/post_transaction_uphold/post_transaction_uphold.cc
index b11e972ec48..4d3d14b2824 100644
--- a/components/brave_rewards/core/endpoint/payment/post_transaction_uphold/post_transaction_uphold.cc
+++ b/components/brave_rewards/core/endpoint/payment/post_transaction_uphold/post_transaction_uphold.cc
@@ -14,9 +14,7 @@
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 #include "net/http/http_status_code.h"
 
-namespace brave_rewards::internal {
-namespace endpoint {
-namespace payment {
+namespace brave_rewards::internal::endpoint::payment {
 
 PostTransactionUphold::PostTransactionUphold(RewardsEngine& engine)
     : engine_(engine) {}
@@ -90,6 +88,4 @@ void PostTransactionUphold::OnRequest(PostTransactionUpholdCallback callback,
   std::move(callback).Run(CheckStatusCode(response->status_code));
 }
 
-}  // namespace payment
-}  // namespace endpoint
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::endpoint::payment
diff --git a/components/brave_rewards/core/endpoint/payment/post_votes/post_votes.cc b/components/brave_rewards/core/endpoint/payment/post_votes/post_votes.cc
index 79e555cd060..7362411da2c 100644
--- a/components/brave_rewards/core/endpoint/payment/post_votes/post_votes.cc
+++ b/components/brave_rewards/core/endpoint/payment/post_votes/post_votes.cc
@@ -15,9 +15,7 @@
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 #include "net/http/http_status_code.h"
 
-namespace brave_rewards::internal {
-namespace endpoint {
-namespace payment {
+namespace brave_rewards::internal::endpoint::payment {
 
 PostVotes::PostVotes(RewardsEngine& engine) : engine_(engine) {}
 
@@ -94,6 +92,4 @@ void PostVotes::OnRequest(PostVotesCallback callback,
   std::move(callback).Run(CheckStatusCode(response->status_code));
 }
 
-}  // namespace payment
-}  // namespace endpoint
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::endpoint::payment
diff --git a/components/brave_rewards/core/endpoint/private_cdn/get_publisher/get_publisher.cc b/components/brave_rewards/core/endpoint/private_cdn/get_publisher/get_publisher.cc
index c6ab70f78a6..6831789b73d 100644
--- a/components/brave_rewards/core/endpoint/private_cdn/get_publisher/get_publisher.cc
+++ b/components/brave_rewards/core/endpoint/private_cdn/get_publisher/get_publisher.cc
@@ -146,8 +146,7 @@ bool DecompressMessage(std::string_view payload, std::string* output) {
 
 }  // namespace
 
-namespace endpoint {
-namespace private_cdn {
+namespace endpoint::private_cdn {
 
 GetPublisher::GetPublisher(RewardsEngine& engine) : engine_(engine) {}
 
@@ -253,6 +252,6 @@ void GetPublisher::OnRequest(const std::string& publisher_key,
   std::move(callback).Run(mojom::Result::OK, std::move(info));
 }
 
-}  // namespace private_cdn
-}  // namespace endpoint
+}  // namespace endpoint::private_cdn
+
 }  // namespace brave_rewards::internal
diff --git a/components/brave_rewards/core/endpoint/private_cdn/private_cdn_server.cc b/components/brave_rewards/core/endpoint/private_cdn/private_cdn_server.cc
index 97323fb52fb..0e6a7f12246 100644
--- a/components/brave_rewards/core/endpoint/private_cdn/private_cdn_server.cc
+++ b/components/brave_rewards/core/endpoint/private_cdn/private_cdn_server.cc
@@ -6,13 +6,11 @@
 
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 
-namespace brave_rewards::internal {
-namespace endpoint {
+namespace brave_rewards::internal::endpoint {
 
 PrivateCDNServer::PrivateCDNServer(RewardsEngine& engine)
     : get_publisher_(engine) {}
 
 PrivateCDNServer::~PrivateCDNServer() = default;
 
-}  // namespace endpoint
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::endpoint
diff --git a/components/brave_rewards/core/endpoint/rewards/get_prefix_list/get_prefix_list.cc b/components/brave_rewards/core/endpoint/rewards/get_prefix_list/get_prefix_list.cc
index 5c09e6ce2fa..d9680af1de9 100644
--- a/components/brave_rewards/core/endpoint/rewards/get_prefix_list/get_prefix_list.cc
+++ b/components/brave_rewards/core/endpoint/rewards/get_prefix_list/get_prefix_list.cc
@@ -12,9 +12,7 @@
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 #include "net/http/http_status_code.h"
 
-namespace brave_rewards::internal {
-namespace endpoint {
-namespace rewards {
+namespace brave_rewards::internal::endpoint::rewards {
 
 GetPrefixList::GetPrefixList(RewardsEngine& engine) : engine_(engine) {}
 
@@ -61,6 +59,4 @@ void GetPrefixList::OnRequest(GetPrefixListCallback callback,
   std::move(callback).Run(mojom::Result::OK, response->body);
 }
 
-}  // namespace rewards
-}  // namespace endpoint
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::endpoint::rewards
diff --git a/components/brave_rewards/core/endpoint/rewards/rewards_server.cc b/components/brave_rewards/core/endpoint/rewards/rewards_server.cc
index 2abd5e00f9d..944dde23938 100644
--- a/components/brave_rewards/core/endpoint/rewards/rewards_server.cc
+++ b/components/brave_rewards/core/endpoint/rewards/rewards_server.cc
@@ -6,13 +6,11 @@
 
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 
-namespace brave_rewards::internal {
-namespace endpoint {
+namespace brave_rewards::internal::endpoint {
 
 RewardsServer::RewardsServer(RewardsEngine& engine)
     : get_prefix_list_(engine) {}
 
 RewardsServer::~RewardsServer() = default;
 
-}  // namespace endpoint
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::endpoint
diff --git a/components/brave_rewards/core/endpoint/uphold/get_capabilities/get_capabilities.cc b/components/brave_rewards/core/endpoint/uphold/get_capabilities/get_capabilities.cc
index c72d5d78109..c4f5dccb450 100644
--- a/components/brave_rewards/core/endpoint/uphold/get_capabilities/get_capabilities.cc
+++ b/components/brave_rewards/core/endpoint/uphold/get_capabilities/get_capabilities.cc
@@ -17,8 +17,7 @@ namespace brave_rewards::internal {
 
 using uphold::Capabilities;
 
-namespace endpoint {
-namespace uphold {
+namespace endpoint::uphold {
 
 GetCapabilities::GetCapabilities(RewardsEngine& engine) : engine_(engine) {}
 
@@ -110,6 +109,6 @@ GetCapabilities::CapabilityMap GetCapabilities::ParseBody(
   return capability_map;
 }
 
-}  // namespace uphold
-}  // namespace endpoint
+}  // namespace endpoint::uphold
+
 }  // namespace brave_rewards::internal
diff --git a/components/brave_rewards/core/endpoint/uphold/get_card/get_card.cc b/components/brave_rewards/core/endpoint/uphold/get_card/get_card.cc
index efe5d9b57c7..0922f512f24 100644
--- a/components/brave_rewards/core/endpoint/uphold/get_card/get_card.cc
+++ b/components/brave_rewards/core/endpoint/uphold/get_card/get_card.cc
@@ -17,9 +17,7 @@
 #include "brave/components/brave_rewards/core/uphold/uphold_card.h"
 #include "net/http/http_status_code.h"
 
-namespace brave_rewards::internal {
-namespace endpoint {
-namespace uphold {
+namespace brave_rewards::internal::endpoint::uphold {
 
 GetCard::GetCard(RewardsEngine& engine) : engine_(engine) {}
 
@@ -103,6 +101,4 @@ void GetCard::OnRequest(GetCardCallback callback,
   std::move(callback).Run(result, available);
 }
 
-}  // namespace uphold
-}  // namespace endpoint
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::endpoint::uphold
diff --git a/components/brave_rewards/core/endpoint/uphold/get_me/get_me.cc b/components/brave_rewards/core/endpoint/uphold/get_me/get_me.cc
index 24fa3327b76..a071d0aea5a 100644
--- a/components/brave_rewards/core/endpoint/uphold/get_me/get_me.cc
+++ b/components/brave_rewards/core/endpoint/uphold/get_me/get_me.cc
@@ -15,9 +15,7 @@
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 #include "net/http/http_status_code.h"
 
-namespace brave_rewards::internal {
-namespace endpoint {
-namespace uphold {
+namespace brave_rewards::internal::endpoint::uphold {
 
 GetMe::GetMe(RewardsEngine& engine) : engine_(engine) {}
 
@@ -103,6 +101,4 @@ void GetMe::OnRequest(GetMeCallback callback, mojom::UrlResponsePtr response) {
   std::move(callback).Run(result, user);
 }
 
-}  // namespace uphold
-}  // namespace endpoint
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::endpoint::uphold
diff --git a/components/brave_rewards/core/endpoint/uphold/uphold_server.cc b/components/brave_rewards/core/endpoint/uphold/uphold_server.cc
index 0ced4be28ac..37e53034f8a 100644
--- a/components/brave_rewards/core/endpoint/uphold/uphold_server.cc
+++ b/components/brave_rewards/core/endpoint/uphold/uphold_server.cc
@@ -7,8 +7,7 @@
 
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 
-namespace brave_rewards::internal {
-namespace endpoint {
+namespace brave_rewards::internal::endpoint {
 
 UpholdServer::UpholdServer(RewardsEngine& engine)
     : get_capabilities_(engine),
@@ -20,5 +19,4 @@ UpholdServer::UpholdServer(RewardsEngine& engine)
 
 UpholdServer::~UpholdServer() = default;
 
-}  // namespace endpoint
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::endpoint
diff --git a/components/brave_rewards/core/legacy/publisher_state.cc b/components/brave_rewards/core/legacy/publisher_state.cc
index b9d439ef272..0dd6d806451 100644
--- a/components/brave_rewards/core/legacy/publisher_state.cc
+++ b/components/brave_rewards/core/legacy/publisher_state.cc
@@ -9,8 +9,7 @@
 #include "brave/components/brave_rewards/core/legacy/publisher_state.h"
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 
-namespace brave_rewards::internal {
-namespace publisher {
+namespace brave_rewards::internal::publisher {
 
 LegacyPublisherState::LegacyPublisherState(RewardsEngine& engine)
     : engine_(engine) {}
@@ -75,5 +74,4 @@ void LegacyPublisherState::GetAllBalanceReports(
   }
 }
 
-}  // namespace publisher
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::publisher
diff --git a/components/brave_rewards/core/logging/event_log_util.cc b/components/brave_rewards/core/logging/event_log_util.cc
index 2324402abfc..434252dd06b 100644
--- a/components/brave_rewards/core/logging/event_log_util.cc
+++ b/components/brave_rewards/core/logging/event_log_util.cc
@@ -6,8 +6,7 @@
 #include "brave/components/brave_rewards/core/logging/event_log_util.h"
 #include "brave/components/brave_rewards/core/logging/event_log_keys.h"
 
-namespace brave_rewards::internal {
-namespace log {
+namespace brave_rewards::internal::log {
 std::string GetEventLogKeyForLinkingResult(
     mojom::ConnectExternalWalletResult result) {
   switch (result) {
@@ -35,5 +34,4 @@ std::string GetEventLogKeyForLinkingResult(
       return "";
   }
 }
-}  // namespace log
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::log
diff --git a/components/brave_rewards/core/publisher/prefix_list_reader.cc b/components/brave_rewards/core/publisher/prefix_list_reader.cc
index 745cbed66fe..8d2986375bc 100644
--- a/components/brave_rewards/core/publisher/prefix_list_reader.cc
+++ b/components/brave_rewards/core/publisher/prefix_list_reader.cc
@@ -11,8 +11,7 @@
 #include "brave/components/brave_rewards/core/publisher/prefix_util.h"
 #include "brave/components/brave_rewards/core/publisher/protos/publisher_prefix_list.pb.h"
 
-namespace brave_rewards::internal {
-namespace publisher {
+namespace brave_rewards::internal::publisher {
 
 PrefixListReader::PrefixListReader() : prefix_size_(kMinPrefixSize) {}
 
@@ -92,5 +91,4 @@ PrefixListReader::ParseError PrefixListReader::Parse(
   return ParseError::kNone;
 }
 
-}  // namespace publisher
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::publisher
diff --git a/components/brave_rewards/core/publisher/prefix_list_reader_unittest.cc b/components/brave_rewards/core/publisher/prefix_list_reader_unittest.cc
index 22edb83f4d4..7503518d4c2 100644
--- a/components/brave_rewards/core/publisher/prefix_list_reader_unittest.cc
+++ b/components/brave_rewards/core/publisher/prefix_list_reader_unittest.cc
@@ -11,8 +11,7 @@
 #include "brave/components/brave_rewards/core/publisher/protos/publisher_prefix_list.pb.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
-namespace brave_rewards::internal {
-namespace publisher {
+namespace brave_rewards::internal::publisher {
 
 class RewardsPrefixListReaderTest : public testing::Test {
  protected:
@@ -159,5 +158,4 @@ TEST_F(RewardsPrefixListReaderTest, BrotliCompression) {
   ASSERT_EQ(uncompressed, "aaaabbbbccccddddeeeeffffgggghhhh");
 }
 
-}  // namespace publisher
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::publisher
diff --git a/components/brave_rewards/core/publisher/prefix_util.cc b/components/brave_rewards/core/publisher/prefix_util.cc
index 0fd2de1bbb1..8abce254953 100644
--- a/components/brave_rewards/core/publisher/prefix_util.cc
+++ b/components/brave_rewards/core/publisher/prefix_util.cc
@@ -8,8 +8,7 @@
 #include "base/strings/string_number_conversions.h"
 #include "crypto/sha2.h"
 
-namespace brave_rewards::internal {
-namespace publisher {
+namespace brave_rewards::internal::publisher {
 
 const size_t kMinPrefixSize = 4;
 const size_t kMaxPrefixSize = 32;
@@ -29,5 +28,4 @@ std::string GetHashPrefixInHex(const std::string& publisher_key,
   return base::HexEncode(raw.data(), raw.size());
 }
 
-}  // namespace publisher
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::publisher
diff --git a/components/brave_rewards/core/publisher/publisher_prefix_list_updater.cc b/components/brave_rewards/core/publisher/publisher_prefix_list_updater.cc
index 98099a77f55..33258120656 100644
--- a/components/brave_rewards/core/publisher/publisher_prefix_list_updater.cc
+++ b/components/brave_rewards/core/publisher/publisher_prefix_list_updater.cc
@@ -21,8 +21,7 @@ constexpr int64_t kMaxRetryAfterFailureDelay = 4 * base::Time::kSecondsPerHour;
 
 }  // namespace
 
-namespace brave_rewards::internal {
-namespace publisher {
+namespace brave_rewards::internal::publisher {
 
 PublisherPrefixListUpdater::PublisherPrefixListUpdater(RewardsEngine& engine)
     : engine_(engine), rewards_server_(engine) {}
@@ -142,5 +141,4 @@ base::TimeDelta PublisherPrefixListUpdater::GetRetryAfterFailureDelay() {
       base::Seconds(kMaxRetryAfterFailureDelay), retry_count_++);
 }
 
-}  // namespace publisher
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::publisher
diff --git a/components/brave_rewards/core/sku/sku.cc b/components/brave_rewards/core/sku/sku.cc
index 87ef3d8c5aa..f4b65db37cd 100644
--- a/components/brave_rewards/core/sku/sku.cc
+++ b/components/brave_rewards/core/sku/sku.cc
@@ -11,8 +11,7 @@
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 #include "brave/components/brave_rewards/core/sku/sku.h"
 
-namespace brave_rewards::internal {
-namespace sku {
+namespace brave_rewards::internal::sku {
 
 SKU::SKU(RewardsEngine& engine) : engine_(engine), common_(engine) {}
 
@@ -131,5 +130,4 @@ void SKU::OnOrder(const std::string& wallet_type,
   }
 }
 
-}  // namespace sku
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::sku
diff --git a/components/brave_rewards/core/sku/sku_common.cc b/components/brave_rewards/core/sku/sku_common.cc
index e5ee926d0d5..fc619f74922 100644
--- a/components/brave_rewards/core/sku/sku_common.cc
+++ b/components/brave_rewards/core/sku/sku_common.cc
@@ -10,8 +10,7 @@
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 #include "brave/components/brave_rewards/core/sku/sku_common.h"
 
-namespace brave_rewards::internal {
-namespace sku {
+namespace brave_rewards::internal::sku {
 
 SKUCommon::SKUCommon(RewardsEngine& engine)
     : engine_(engine), order_(engine), transaction_(engine) {}
@@ -85,5 +84,4 @@ void SKUCommon::GetSKUTransactionByOrderId(
       mojom::Result::OK);
 }
 
-}  // namespace sku
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::sku
diff --git a/components/brave_rewards/core/sku/sku_order.cc b/components/brave_rewards/core/sku/sku_order.cc
index 78b3a260454..4f7b25b7b9b 100644
--- a/components/brave_rewards/core/sku/sku_order.cc
+++ b/components/brave_rewards/core/sku/sku_order.cc
@@ -11,8 +11,7 @@
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 #include "brave/components/brave_rewards/core/sku/sku_order.h"
 
-namespace brave_rewards::internal {
-namespace sku {
+namespace brave_rewards::internal::sku {
 
 SKUOrder::SKUOrder(RewardsEngine& engine)
     : engine_(engine), payment_server_(engine) {}
@@ -59,5 +58,4 @@ void SKUOrder::OnCreateSave(const std::string& order_id,
   std::move(callback).Run(mojom::Result::OK, order_id);
 }
 
-}  // namespace sku
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::sku
diff --git a/components/brave_rewards/core/state/state_migration.cc b/components/brave_rewards/core/state/state_migration.cc
index 7c03cc896db..b9edd8f91c8 100644
--- a/components/brave_rewards/core/state/state_migration.cc
+++ b/components/brave_rewards/core/state/state_migration.cc
@@ -15,8 +15,7 @@ const int kCurrentVersionNumber = 14;
 
 }  // namespace
 
-namespace brave_rewards::internal {
-namespace state {
+namespace brave_rewards::internal::state {
 
 StateMigration::StateMigration(RewardsEngine& engine)
     : engine_(engine),
@@ -160,5 +159,4 @@ void StateMigration::OnMigration(ResultCallback callback,
   Migrate(std::move(callback));
 }
 
-}  // namespace state
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::state
diff --git a/components/brave_rewards/core/state/state_migration_v1.cc b/components/brave_rewards/core/state/state_migration_v1.cc
index 0f97c71357f..6ef3e07a503 100644
--- a/components/brave_rewards/core/state/state_migration_v1.cc
+++ b/components/brave_rewards/core/state/state_migration_v1.cc
@@ -11,8 +11,7 @@
 #include "brave/components/brave_rewards/core/state/state_keys.h"
 #include "brave/components/brave_rewards/core/state/state_migration_v1.h"
 
-namespace brave_rewards::internal {
-namespace state {
+namespace brave_rewards::internal::state {
 
 StateMigrationV1::StateMigrationV1(RewardsEngine& engine) : engine_(engine) {}
 
@@ -78,5 +77,4 @@ void StateMigrationV1::BalanceReportsSaved(ResultCallback callback,
   std::move(callback).Run(mojom::Result::OK);
 }
 
-}  // namespace state
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::state
diff --git a/components/brave_rewards/core/state/state_migration_v11.cc b/components/brave_rewards/core/state/state_migration_v11.cc
index 542a19301e6..829560c44a5 100644
--- a/components/brave_rewards/core/state/state_migration_v11.cc
+++ b/components/brave_rewards/core/state/state_migration_v11.cc
@@ -12,8 +12,7 @@
 #include "brave/components/brave_rewards/core/state/state.h"
 #include "brave/components/brave_rewards/core/state/state_keys.h"
 
-namespace brave_rewards::internal {
-namespace state {
+namespace brave_rewards::internal::state {
 
 StateMigrationV11::StateMigrationV11(RewardsEngine& engine) : engine_(engine) {}
 
@@ -33,5 +32,4 @@ void StateMigrationV11::Migrate(ResultCallback callback) {
   std::move(callback).Run(mojom::Result::OK);
 }
 
-}  // namespace state
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::state
diff --git a/components/brave_rewards/core/state/state_migration_v2.cc b/components/brave_rewards/core/state/state_migration_v2.cc
index 49a07d008e4..d471b86bce4 100644
--- a/components/brave_rewards/core/state/state_migration_v2.cc
+++ b/components/brave_rewards/core/state/state_migration_v2.cc
@@ -10,8 +10,7 @@
 #include "brave/components/brave_rewards/core/state/state_keys.h"
 #include "brave/components/brave_rewards/core/state/state_migration_v2.h"
 
-namespace brave_rewards::internal {
-namespace state {
+namespace brave_rewards::internal::state {
 
 StateMigrationV2::StateMigrationV2(RewardsEngine& engine) : engine_(engine) {}
 
@@ -62,5 +61,4 @@ void StateMigrationV2::OnLoadState(ResultCallback callback,
   std::move(callback).Run(mojom::Result::OK);
 }
 
-}  // namespace state
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::state
diff --git a/components/brave_rewards/core/state/state_migration_v3.cc b/components/brave_rewards/core/state/state_migration_v3.cc
index 9da83b66445..db3ce138dc3 100644
--- a/components/brave_rewards/core/state/state_migration_v3.cc
+++ b/components/brave_rewards/core/state/state_migration_v3.cc
@@ -7,8 +7,7 @@
 
 #include <utility>
 
-namespace brave_rewards::internal {
-namespace state {
+namespace brave_rewards::internal::state {
 
 StateMigrationV3::StateMigrationV3() = default;
 
@@ -21,5 +20,4 @@ void StateMigrationV3::Migrate(ResultCallback callback) {
   std::move(callback).Run(mojom::Result::OK);
 }
 
-}  // namespace state
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::state
diff --git a/components/brave_rewards/core/state/state_migration_v4.cc b/components/brave_rewards/core/state/state_migration_v4.cc
index ea635828347..8894eb5dc5d 100644
--- a/components/brave_rewards/core/state/state_migration_v4.cc
+++ b/components/brave_rewards/core/state/state_migration_v4.cc
@@ -9,8 +9,7 @@
 
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 
-namespace brave_rewards::internal {
-namespace state {
+namespace brave_rewards::internal::state {
 
 StateMigrationV4::StateMigrationV4(RewardsEngine& engine) : engine_(engine) {}
 
@@ -20,5 +19,4 @@ void StateMigrationV4::Migrate(ResultCallback callback) {
   engine_->client()->DeleteLog(std::move(callback));
 }
 
-}  // namespace state
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::state
diff --git a/components/brave_rewards/core/state/state_migration_v5.cc b/components/brave_rewards/core/state/state_migration_v5.cc
index f2b9fa25bbf..becd5548307 100644
--- a/components/brave_rewards/core/state/state_migration_v5.cc
+++ b/components/brave_rewards/core/state/state_migration_v5.cc
@@ -12,8 +12,7 @@
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 #include "brave/components/brave_rewards/core/state/state_keys.h"
 
-namespace brave_rewards::internal {
-namespace state {
+namespace brave_rewards::internal::state {
 
 StateMigrationV5::StateMigrationV5(RewardsEngine& engine) : engine_(engine) {}
 
@@ -59,5 +58,4 @@ void StateMigrationV5::Migrate(ResultCallback callback) {
   engine_->database()->SaveEventLogs(events, std::move(callback));
 }
 
-}  // namespace state
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::state
diff --git a/components/brave_rewards/core/state/state_migration_v6.cc b/components/brave_rewards/core/state/state_migration_v6.cc
index a4ddec943b8..69337a0f34e 100644
--- a/components/brave_rewards/core/state/state_migration_v6.cc
+++ b/components/brave_rewards/core/state/state_migration_v6.cc
@@ -13,8 +13,7 @@
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 #include "brave/components/brave_rewards/core/state/state_keys.h"
 
-namespace brave_rewards::internal {
-namespace state {
+namespace brave_rewards::internal::state {
 
 StateMigrationV6::StateMigrationV6(RewardsEngine& engine) : engine_(engine) {}
 
@@ -36,5 +35,4 @@ void StateMigrationV6::Migrate(ResultCallback callback) {
   std::move(callback).Run(mojom::Result::OK);
 }
 
-}  // namespace state
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::state
diff --git a/components/brave_rewards/core/state/state_migration_v7.cc b/components/brave_rewards/core/state/state_migration_v7.cc
index 9ff1772bde6..dd109d322ea 100644
--- a/components/brave_rewards/core/state/state_migration_v7.cc
+++ b/components/brave_rewards/core/state/state_migration_v7.cc
@@ -11,8 +11,7 @@
 #include "brave/components/brave_rewards/core/state/state.h"
 #include "brave/components/brave_rewards/core/state/state_keys.h"
 
-namespace brave_rewards::internal {
-namespace state {
+namespace brave_rewards::internal::state {
 
 StateMigrationV7::StateMigrationV7(RewardsEngine& engine) : engine_(engine) {}
 
@@ -36,5 +35,4 @@ void StateMigrationV7::Migrate(ResultCallback callback) {
   std::move(callback).Run(mojom::Result::OK);
 }
 
-}  // namespace state
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::state
diff --git a/components/brave_rewards/core/state/state_migration_v8.cc b/components/brave_rewards/core/state/state_migration_v8.cc
index cd8f8f5d263..38126165c6f 100644
--- a/components/brave_rewards/core/state/state_migration_v8.cc
+++ b/components/brave_rewards/core/state/state_migration_v8.cc
@@ -10,8 +10,7 @@
 #include "brave/components/brave_rewards/core/rewards_engine.h"
 #include "brave/components/brave_rewards/core/state/state_keys.h"
 
-namespace brave_rewards::internal {
-namespace state {
+namespace brave_rewards::internal::state {
 
 StateMigrationV8::StateMigrationV8(RewardsEngine& engine) : engine_(engine) {}
 
@@ -27,5 +26,4 @@ void StateMigrationV8::Migrate(ResultCallback callback) {
   std::move(callback).Run(mojom::Result::OK);
 }
 
-}  // namespace state
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::state
diff --git a/components/brave_rewards/core/state/state_migration_v9.cc b/components/brave_rewards/core/state/state_migration_v9.cc
index bf32c772477..4d26256156a 100644
--- a/components/brave_rewards/core/state/state_migration_v9.cc
+++ b/components/brave_rewards/core/state/state_migration_v9.cc
@@ -7,8 +7,7 @@
 
 #include <utility>
 
-namespace brave_rewards::internal {
-namespace state {
+namespace brave_rewards::internal::state {
 
 StateMigrationV9::StateMigrationV9() = default;
 
@@ -22,5 +21,4 @@ void StateMigrationV9::Migrate(ResultCallback callback) {
   std::move(callback).Run(mojom::Result::OK);
 }
 
-}  // namespace state
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::state
diff --git a/components/brave_rewards/core/wallet/wallet.cc b/components/brave_rewards/core/wallet/wallet.cc
index e9414f6e2a9..47756f7c056 100644
--- a/components/brave_rewards/core/wallet/wallet.cc
+++ b/components/brave_rewards/core/wallet/wallet.cc
@@ -21,8 +21,7 @@
 #include "brave/components/brave_rewards/core/wallet/wallet_util.h"
 #include "wally_bip39.h"  // NOLINT
 
-namespace brave_rewards::internal {
-namespace wallet {
+namespace brave_rewards::internal::wallet {
 
 Wallet::Wallet(RewardsEngine& engine)
     : engine_(engine), create_(engine), balance_(engine) {}
@@ -119,5 +118,4 @@ bool Wallet::SetWallet(mojom::RewardsWalletPtr wallet) {
   return true;
 }
 
-}  // namespace wallet
-}  // namespace brave_rewards::internal
+}  // namespace brave_rewards::internal::wallet
diff --git a/components/brave_search/common/features.cc b/components/brave_search/common/features.cc
index 2ae486a97d2..d1656ae54a1 100644
--- a/components/brave_search/common/features.cc
+++ b/components/brave_search/common/features.cc
@@ -7,8 +7,7 @@
 
 #include "base/feature_list.h"
 
-namespace brave_search {
-namespace features {
+namespace brave_search::features {
 
 BASE_FEATURE(kBraveSearchDefaultAPIFeature,
              "BraveSearchDefaultAPI",
@@ -20,5 +19,4 @@ const base::FeatureParam<int> kBraveSearchDefaultAPIDailyLimit{
 const base::FeatureParam<int> kBraveSearchDefaultAPITotalLimit{
     &kBraveSearchDefaultAPIFeature, kBraveSearchDefaultAPITotalLimitName, 10};
 
-}  // namespace features
-}  // namespace brave_search
+}  // namespace brave_search::features
diff --git a/components/brave_search_conversion/features.cc b/components/brave_search_conversion/features.cc
index 44059517191..4505627adb9 100644
--- a/components/brave_search_conversion/features.cc
+++ b/components/brave_search_conversion/features.cc
@@ -5,9 +5,7 @@
 
 #include "brave/components/brave_search_conversion/features.h"
 
-namespace brave_search_conversion {
-
-namespace features {
+namespace brave_search_conversion::features {
 
 // Brave search promotion match located at last low in omnibox popup.
 // This type seems more like ads banner.
@@ -25,6 +23,4 @@ BASE_FEATURE(kOmniboxDDGBanner,
 // Brave search promotion at NTP.
 BASE_FEATURE(kNTP, "BraveSearchNTP", base::FEATURE_DISABLED_BY_DEFAULT);
 
-}  // namespace features
-
-}  // namespace brave_search_conversion
+}  // namespace brave_search_conversion::features
diff --git a/components/brave_search_conversion/p3a.cc b/components/brave_search_conversion/p3a.cc
index 0aef728ccda..9e7547a7a77 100644
--- a/components/brave_search_conversion/p3a.cc
+++ b/components/brave_search_conversion/p3a.cc
@@ -15,8 +15,7 @@
 #include "components/prefs/pref_service.h"
 #include "components/prefs/scoped_user_pref_update.h"
 
-namespace brave_search_conversion {
-namespace p3a {
+namespace brave_search_conversion::p3a {
 
 namespace {
 
@@ -289,5 +288,4 @@ void RecordDefaultEngineChurn(PrefService* prefs) {
   prefs->ClearPref(prefs::kP3AQueryCountBeforeChurn);
 }
 
-}  // namespace p3a
-}  // namespace brave_search_conversion
+}  // namespace brave_search_conversion::p3a
diff --git a/components/brave_search_conversion/p3a_unittest.cc b/components/brave_search_conversion/p3a_unittest.cc
index ba043d060e2..8cb1df91098 100644
--- a/components/brave_search_conversion/p3a_unittest.cc
+++ b/components/brave_search_conversion/p3a_unittest.cc
@@ -10,8 +10,7 @@
 #include "components/prefs/testing_pref_service.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
-namespace brave_search_conversion {
-namespace p3a {
+namespace brave_search_conversion::p3a {
 
 struct ConversionTypeInfo {
   ConversionType type;
@@ -153,5 +152,4 @@ TEST_F(BraveSearchConversionP3ATest, TestQueriesBeforeChurn) {
                                       1);
 }
 
-}  // namespace p3a
-}  // namespace brave_search_conversion
+}  // namespace brave_search_conversion::p3a
diff --git a/components/brave_shields/core/common/features.cc b/components/brave_shields/core/common/features.cc
index 03a1566cf78..bef6ad9123a 100644
--- a/components/brave_shields/core/common/features.cc
+++ b/components/brave_shields/core/common/features.cc
@@ -7,8 +7,7 @@
 
 #include "base/feature_list.h"
 
-namespace brave_shields {
-namespace features {
+namespace brave_shields::features {
 
 BASE_FEATURE(kAdBlockDefaultResourceUpdateInterval,
              "AdBlockDefaultResourceUpdateInterval",
@@ -146,5 +145,4 @@ constexpr base::FeatureParam<int>
     kAdblockOverrideRegexDiscardPolicyDiscardUnusedSec{
         &kAdblockOverrideRegexDiscardPolicy, "discard_unused_sec", 180};
 
-}  // namespace features
-}  // namespace brave_shields
+}  // namespace brave_shields::features
diff --git a/components/brave_sync/brave_sync_p3a.cc b/components/brave_sync/brave_sync_p3a.cc
index 26683686b67..ebec9ed467a 100644
--- a/components/brave_sync/brave_sync_p3a.cc
+++ b/components/brave_sync/brave_sync_p3a.cc
@@ -8,8 +8,7 @@
 #include "brave/components/p3a_utils/bucket.h"
 #include "components/sync/base/user_selectable_type.h"
 
-namespace brave_sync {
-namespace p3a {
+namespace brave_sync::p3a {
 
 void RecordEnabledTypes(bool sync_everything_enabled,
                         const syncer::UserSelectableTypeSet& selected_types) {
@@ -55,5 +54,4 @@ void RecordSyncedObjectsCount(int total_entities) {
                                      {1000, 10000, 49000}, total_entities);
 }
 
-}  // namespace p3a
-}  // namespace brave_sync
+}  // namespace brave_sync::p3a
diff --git a/components/brave_sync/brave_sync_p3a_unittest.cc b/components/brave_sync/brave_sync_p3a_unittest.cc
index 9158476e959..5ee468fe505 100644
--- a/components/brave_sync/brave_sync_p3a_unittest.cc
+++ b/components/brave_sync/brave_sync_p3a_unittest.cc
@@ -9,8 +9,7 @@
 #include "components/sync/base/user_selectable_type.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
-namespace brave_sync {
-namespace p3a {
+namespace brave_sync::p3a {
 
 TEST(BraveSyncP3ATest, TestEnabledTypes) {
   using syncer::UserSelectableType;
@@ -76,5 +75,4 @@ TEST(BraveSyncP3ATest, TestSyncedObjectsCount) {
   histogram_tester.ExpectBucketCount(kSyncedObjectsCountHistogramNameV2, 3, 1);
 }
 
-}  // namespace p3a
-}  // namespace brave_sync
+}  // namespace brave_sync::p3a
diff --git a/components/brave_sync/crypto/crypto.cc b/components/brave_sync/crypto/crypto.cc
index 09d42803b79..2e79c1dc272 100644
--- a/components/brave_sync/crypto/crypto.cc
+++ b/components/brave_sync/crypto/crypto.cc
@@ -15,8 +15,7 @@
 #include "third_party/boringssl/src/include/openssl/digest.h"
 #include "third_party/boringssl/src/include/openssl/hkdf.h"
 
-namespace brave_sync {
-namespace crypto {
+namespace brave_sync::crypto {
 
 std::vector<uint8_t> GetSeed(size_t size) {
   if (size < DEFAULT_SEED_SIZE) {
@@ -162,5 +161,4 @@ bool IsPassphraseValid(const std::string& passphrase) {
   return PassphraseToBytes32(passphrase, &bytes);
 }
 
-}  // namespace crypto
-}  // namespace brave_sync
+}  // namespace brave_sync::crypto
diff --git a/components/brave_sync/crypto/crypto_unittest.cc b/components/brave_sync/crypto/crypto_unittest.cc
index 2a796c29ff0..b89b711eecd 100644
--- a/components/brave_sync/crypto/crypto_unittest.cc
+++ b/components/brave_sync/crypto/crypto_unittest.cc
@@ -13,8 +13,7 @@
 #include "crypto/random.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
-namespace brave_sync {
-namespace crypto {
+namespace brave_sync::crypto {
 
 TEST(CryptoTest, GetSeed) {
   std::vector<uint8_t> seed = GetSeed();
@@ -251,5 +250,4 @@ TEST(CryptoTest, Passphrase) {
   EXPECT_FALSE(IsPassphraseValid(bip_invalid_passphrase));
 }
 
-}  // namespace crypto
-}  // namespace brave_sync
+}  // namespace brave_sync::crypto
diff --git a/components/brave_sync/features.cc b/components/brave_sync/features.cc
index 853473dec42..9d6418bc869 100644
--- a/components/brave_sync/features.cc
+++ b/components/brave_sync/features.cc
@@ -7,10 +7,8 @@
 
 #include "base/feature_list.h"
 
-namespace brave_sync {
-namespace features {
+namespace brave_sync::features {
 
 BASE_FEATURE(kBraveSync, "BraveSync", base::FEATURE_ENABLED_BY_DEFAULT);
 
-}  // namespace features
-}  // namespace brave_sync
+}  // namespace brave_sync::features
diff --git a/components/brave_wallet/browser/eth_gas_utils.cc b/components/brave_wallet/browser/eth_gas_utils.cc
index 4b7516e47b4..0e1b9344acf 100644
--- a/components/brave_wallet/browser/eth_gas_utils.cc
+++ b/components/brave_wallet/browser/eth_gas_utils.cc
@@ -13,9 +13,7 @@
 #include "base/logging.h"
 #include "brave/components/brave_wallet/common/hex_utils.h"
 
-namespace brave_wallet {
-
-namespace eth {
+namespace brave_wallet::eth {
 
 // Scale the base fee by 33% to get a suggested value. This is done to account
 // for sufficient fluctionations in the base fee, so that the transaction will
@@ -155,6 +153,4 @@ bool GetSuggested1559Fees(const std::vector<std::string>& base_fee_per_gas,
   return true;
 }
 
-}  // namespace eth
-
-}  // namespace brave_wallet
+}  // namespace brave_wallet::eth
diff --git a/components/brave_wallet/browser/eth_gas_utils_unittest.cc b/components/brave_wallet/browser/eth_gas_utils_unittest.cc
index b19182887fc..16e9b36237f 100644
--- a/components/brave_wallet/browser/eth_gas_utils_unittest.cc
+++ b/components/brave_wallet/browser/eth_gas_utils_unittest.cc
@@ -11,9 +11,7 @@
 #include "brave/components/brave_wallet/common/hex_utils.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
-namespace brave_wallet {
-
-namespace eth {
+namespace brave_wallet::eth {
 
 TEST(EthGasUtilsTest, ScaleBaseFeePerGas) {
   // OK: scale 0x64 (100)
@@ -86,6 +84,4 @@ TEST(EthGasUtilsTest, GetSuggested1559Fees) {
       &suggested_base_fee_per_gas));
 }
 
-}  // namespace eth
-
-}  // namespace brave_wallet
+}  // namespace brave_wallet::eth
diff --git a/components/brave_wallet/browser/eth_requests.cc b/components/brave_wallet/browser/eth_requests.cc
index ec1429c7524..1f2bee64c78 100644
--- a/components/brave_wallet/browser/eth_requests.cc
+++ b/components/brave_wallet/browser/eth_requests.cc
@@ -10,9 +10,7 @@
 #include "brave/components/brave_wallet/browser/json_rpc_requests_helper.h"
 #include "brave/components/brave_wallet/common/hex_utils.h"
 
-namespace brave_wallet {
-
-namespace eth {
+namespace brave_wallet::eth {
 
 std::string web3_clientVersion() {
   return GetJsonRpcString("web3_clientVersion");
@@ -344,6 +342,4 @@ std::string eth_getLogs(base::Value::Dict filter_options) {
   return GetJSON(dictionary);
 }
 
-}  // namespace eth
-
-}  // namespace brave_wallet
+}  // namespace brave_wallet::eth
diff --git a/components/brave_wallet/browser/eth_requests_unittest.cc b/components/brave_wallet/browser/eth_requests_unittest.cc
index f70f8aa27ca..e39812452e8 100644
--- a/components/brave_wallet/browser/eth_requests_unittest.cc
+++ b/components/brave_wallet/browser/eth_requests_unittest.cc
@@ -10,9 +10,7 @@
 #include "brave/components/brave_wallet/browser/eth_requests.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
-namespace brave_wallet {
-
-namespace eth {
+namespace brave_wallet::eth {
 
 TEST(EthRequestUnitTest, web3_clientVersion) {
   ASSERT_EQ(
@@ -351,6 +349,4 @@ TEST(EthRequestUnitTest, eth_getLogs) {
       R"({"id":1,"jsonrpc":"2.0","method":"eth_getLogs","params":[{"address":["0x8888f1f195afa192cfee860698584c030f4c9db1"],"blockhash":"0xb903239f8543d04b5dc1ba6579132b143087c68db1b2168786408fcbce568238","fromBlock":"0x1","toBlock":"0x2","topics":["0x000000000000000000000000a94f5374fce5edbc8e2a8697c15331677e6ebf0b",["0x000000000000000000000000a94f5374fce5edbc8e2a8697c15331677e6ebf0b","0x0000000000000000000000000aff3454fce5edbc8cca8697c15331677e6ebccc"]]}]})");  // NOLINT
 }
 
-}  // namespace eth
-
-}  // namespace brave_wallet
+}  // namespace brave_wallet::eth
diff --git a/components/brave_wallet/browser/eth_response_parser.cc b/components/brave_wallet/browser/eth_response_parser.cc
index d100652e0ff..097d6b74748 100644
--- a/components/brave_wallet/browser/eth_response_parser.cc
+++ b/components/brave_wallet/browser/eth_response_parser.cc
@@ -19,9 +19,7 @@
 #include "net/base/data_url.h"
 #include "tools/json_schema_compiler/util.h"
 
-namespace brave_wallet {
-
-namespace eth {
+namespace brave_wallet::eth {
 
 bool ParseStringResult(const base::Value& json_value, std::string* value) {
   DCHECK(value);
@@ -393,6 +391,4 @@ bool ParseDataURIAndExtractJSON(const GURL url, std::string* json) {
   return true;
 }
 
-}  // namespace eth
-
-}  // namespace brave_wallet
+}  // namespace brave_wallet::eth
diff --git a/components/brave_wallet/browser/eth_response_parser_unittest.cc b/components/brave_wallet/browser/eth_response_parser_unittest.cc
index 286931c3149..71dfadaa1c7 100644
--- a/components/brave_wallet/browser/eth_response_parser_unittest.cc
+++ b/components/brave_wallet/browser/eth_response_parser_unittest.cc
@@ -18,9 +18,7 @@
 
 using base::test::ParseJson;
 
-namespace brave_wallet {
-
-namespace eth {
+namespace brave_wallet::eth {
 
 TEST(EthResponseParserUnitTest, ParseEthGetBalance) {
   std::string json(
@@ -768,6 +766,4 @@ TEST(EthResponseParserUnitTest, DecodeGetERC20TokenBalancesEthCallResponse) {
       "0x0000000000000000000000000000000000000000000000000000000000000000");
 }
 
-}  // namespace eth
-
-}  // namespace brave_wallet
+}  // namespace brave_wallet::eth
diff --git a/components/brave_wallet/browser/fil_requests.cc b/components/brave_wallet/browser/fil_requests.cc
index 587865c9ddc..b98345d3ed4 100644
--- a/components/brave_wallet/browser/fil_requests.cc
+++ b/components/brave_wallet/browser/fil_requests.cc
@@ -16,9 +16,7 @@
 #include "brave/components/brave_wallet/common/fil_address.h"
 #include "brave/components/json/rs/src/lib.rs.h"
 
-namespace brave_wallet {
-
-namespace fil {
+namespace brave_wallet::fil {
 
 std::string getBalance(const std::string& address) {
   return GetJsonRpcString("Filecoin.WalletBalance", address);
@@ -122,6 +120,4 @@ std::optional<std::string> getSendTransaction(const std::string& signed_tx) {
   return FilTransaction::ConvertSignedTxStringFieldsToInt64("/params/0", json);
 }
 
-}  // namespace fil
-
-}  // namespace brave_wallet
+}  // namespace brave_wallet::fil
diff --git a/components/brave_wallet/browser/solana_instruction_builder_unittest.cc b/components/brave_wallet/browser/solana_instruction_builder_unittest.cc
index 5107f5ae02f..2ab86810b6b 100644
--- a/components/brave_wallet/browser/solana_instruction_builder_unittest.cc
+++ b/components/brave_wallet/browser/solana_instruction_builder_unittest.cc
@@ -15,9 +15,7 @@
 #include "brave/components/brave_wallet/common/brave_wallet_constants.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
-namespace brave_wallet {
-
-namespace solana {
+namespace brave_wallet::solana {
 
 namespace system_program {
 
@@ -161,6 +159,4 @@ TEST(SolanaInstructionBuilderUnitTest, SetComputeUnitPrice) {
 
 }  // namespace compute_budget_program
 
-}  // namespace solana
-
-}  // namespace brave_wallet
+}  // namespace brave_wallet::solana
diff --git a/components/brave_wallet/browser/solana_requests.cc b/components/brave_wallet/browser/solana_requests.cc
index 781e306b467..7480d613bfb 100644
--- a/components/brave_wallet/browser/solana_requests.cc
+++ b/components/brave_wallet/browser/solana_requests.cc
@@ -13,9 +13,7 @@
 #include "brave/components/brave_wallet/common/solana_utils.h"
 #include "brave/components/json/rs/src/lib.rs.h"
 
-namespace brave_wallet {
-
-namespace solana {
+namespace brave_wallet::solana {
 
 std::string getBalance(const std::string& pubkey) {
   return GetJsonRpcString("getBalance", pubkey);
@@ -176,6 +174,4 @@ std::string getRecentPrioritizationFees() {
   return GetJsonRpcString("getRecentPrioritizationFees");
 }
 
-}  // namespace solana
-
-}  // namespace brave_wallet
+}  // namespace brave_wallet::solana
diff --git a/components/brave_wallet/browser/solana_requests_unittest.cc b/components/brave_wallet/browser/solana_requests_unittest.cc
index 195c9d819e8..9e8a16334a2 100644
--- a/components/brave_wallet/browser/solana_requests_unittest.cc
+++ b/components/brave_wallet/browser/solana_requests_unittest.cc
@@ -19,9 +19,7 @@ constexpr char kBlockhash[] = "J7rBdM6AecPDEZp8aPq5iPSNKVkU5Q76F3oAV4eW5wsW";
 
 }
 
-namespace brave_wallet {
-
-namespace solana {
+namespace brave_wallet::solana {
 
 TEST(SolanaRequestsUnitTest, getBalance) {
   ASSERT_EQ(
@@ -201,6 +199,4 @@ TEST(SolanaRequestsUnitTest, getRecentPrioritizationFees) {
               })"));
 }
 
-}  // namespace solana
-
-}  // namespace brave_wallet
+}  // namespace brave_wallet::solana
diff --git a/components/brave_wallet/browser/solana_response_parser_unittest.cc b/components/brave_wallet/browser/solana_response_parser_unittest.cc
index 95fbbf9526d..fd163885f6a 100644
--- a/components/brave_wallet/browser/solana_response_parser_unittest.cc
+++ b/components/brave_wallet/browser/solana_response_parser_unittest.cc
@@ -16,9 +16,7 @@
 
 using base::test::ParseJson;
 
-namespace brave_wallet {
-
-namespace solana {
+namespace brave_wallet::solana {
 
 TEST(SolanaResponseParserUnitTest, ParseSolanaGetBalance) {
   std::string json =
@@ -897,6 +895,4 @@ TEST(SolanaResponseParserUnitTest, ParseGetSolanaPrioritizationFees) {
   EXPECT_FALSE(fees.has_value());
 }
 
-}  // namespace solana
-
-}  // namespace brave_wallet
+}  // namespace brave_wallet::solana
diff --git a/components/brave_wallet/common/features.cc b/components/brave_wallet/common/features.cc
index 1d720022ffd..faebbf847c4 100644
--- a/components/brave_wallet/common/features.cc
+++ b/components/brave_wallet/common/features.cc
@@ -9,8 +9,7 @@
 #include "brave/components/brave_wallet/common/buildflags.h"
 #include "build/build_config.h"
 
-namespace brave_wallet {
-namespace features {
+namespace brave_wallet::features {
 
 BASE_FEATURE(kNativeBraveWalletFeature,
              "NativeBraveWallet",
@@ -61,5 +60,4 @@ BASE_FEATURE(kBraveWalletAnkrBalancesFeature,
 BASE_FEATURE(kBraveWalletTransactionSimulationsFeature,
              "BraveWalletTransactionSimulations",
              base::FEATURE_DISABLED_BY_DEFAULT);
-}  // namespace features
-}  // namespace brave_wallet
+}  // namespace brave_wallet::features
diff --git a/components/brave_welcome/common/features.cc b/components/brave_welcome/common/features.cc
index 2752e0c561c..c46d473a79c 100644
--- a/components/brave_welcome/common/features.cc
+++ b/components/brave_welcome/common/features.cc
@@ -7,12 +7,10 @@
 
 #include "base/feature_list.h"
 
-namespace brave_welcome {
-namespace features {
+namespace brave_welcome::features {
 
 BASE_FEATURE(kShowRewardsCard,
              "ShowRewardsCard",
              base::FEATURE_DISABLED_BY_DEFAULT);
 
-}  // namespace features
-}  // namespace brave_welcome
+}  // namespace brave_welcome::features
diff --git a/components/de_amp/common/features.cc b/components/de_amp/common/features.cc
index 7d87b92dc36..bb9565196dd 100644
--- a/components/de_amp/common/features.cc
+++ b/components/de_amp/common/features.cc
@@ -8,12 +8,10 @@
 #include "base/feature_list.h"
 #include "build/build_config.h"
 
-namespace de_amp {
-namespace features {
+namespace de_amp::features {
 
 // When enabled, Brave will try to de-AMP a page i.e. load the canonical,
 // non-AMP version if the page is an AMP page.
 BASE_FEATURE(kBraveDeAMP, "BraveDeAMP", base::FEATURE_ENABLED_BY_DEFAULT);
 
-}  // namespace features
-}  // namespace de_amp
+}  // namespace de_amp::features
diff --git a/components/debounce/core/common/features.cc b/components/debounce/core/common/features.cc
index 81f92399f55..436d0deceee 100644
--- a/components/debounce/core/common/features.cc
+++ b/components/debounce/core/common/features.cc
@@ -7,8 +7,7 @@
 
 #include "base/feature_list.h"
 
-namespace debounce {
-namespace features {
+namespace debounce::features {
 
 // When enabled, Brave will try to parse tracking URLs of the form
 // https://tracker.example.com/?url=http://final.example.com/
@@ -16,5 +15,4 @@ namespace features {
 // network requests to the tracker.
 BASE_FEATURE(kBraveDebounce, "BraveDebounce", base::FEATURE_ENABLED_BY_DEFAULT);
 
-}  // namespace features
-}  // namespace debounce
+}  // namespace debounce::features
diff --git a/components/ipfs/features.cc b/components/ipfs/features.cc
index b35e2a05746..1b35ee63dd8 100644
--- a/components/ipfs/features.cc
+++ b/components/ipfs/features.cc
@@ -8,8 +8,7 @@
 #include "base/feature_list.h"
 #include "brave/components/ipfs/buildflags/buildflags.h"
 
-namespace ipfs {
-namespace features {
+namespace ipfs::features {
 
 BASE_FEATURE(kIpfsFeature,
              "Ipfs",
@@ -20,5 +19,4 @@ BASE_FEATURE(kIpfsFeature,
 #endif
 );
 
-}  // namespace features
-}  // namespace ipfs
+}  // namespace ipfs::features
diff --git a/components/ntp_background_images/browser/features.cc b/components/ntp_background_images/browser/features.cc
index a5663219d15..a41c4f63b1f 100644
--- a/components/ntp_background_images/browser/features.cc
+++ b/components/ntp_background_images/browser/features.cc
@@ -9,8 +9,7 @@
 #include "build/build_config.h"
 #include "ui/base/ui_base_features.h"
 
-namespace ntp_background_images {
-namespace features {
+namespace ntp_background_images::features {
 
 BASE_FEATURE(kBraveNTPBrandedWallpaperDemo,
              "BraveNTPBrandedWallpaperDemoName",
@@ -30,5 +29,4 @@ BASE_FEATURE(kBraveNTPBrandedWallpaper,
              "BraveNTPBrandedWallpaper",
              base::FEATURE_ENABLED_BY_DEFAULT);
 
-}  // namespace features
-}  // namespace ntp_background_images
+}  // namespace ntp_background_images::features
diff --git a/components/p3a/features.cc b/components/p3a/features.cc
index 5d24169532f..4000de6254a 100644
--- a/components/p3a/features.cc
+++ b/components/p3a/features.cc
@@ -6,8 +6,7 @@
 #include "brave/components/p3a/features.h"
 #include "brave/components/p3a/metric_log_type.h"
 
-namespace p3a {
-namespace features {
+namespace p3a::features {
 
 BASE_FEATURE(kConstellation,
              "BraveP3AConstellation",
@@ -38,5 +37,4 @@ bool IsJSONDeprecated(MetricLogType log_type) {
   return base::FeatureList::IsEnabled(features::kOtherJSONDeprecation);
 }
 
-}  // namespace features
-}  // namespace p3a
+}  // namespace p3a::features
diff --git a/components/request_otr/browser/request_otr_p3a.cc b/components/request_otr/browser/request_otr_p3a.cc
index 69a97cf81b4..d095cea11a2 100644
--- a/components/request_otr/browser/request_otr_p3a.cc
+++ b/components/request_otr/browser/request_otr_p3a.cc
@@ -9,8 +9,7 @@
 #include "brave/components/time_period_storage/monthly_storage.h"
 #include "components/prefs/pref_registry_simple.h"
 
-namespace request_otr {
-namespace p3a {
+namespace request_otr::p3a {
 
 namespace {
 
@@ -74,5 +73,4 @@ void UpdateMetrics(PrefService* prefs) {
   RecordInterstitialEnd(prefs, {});
 }
 
-}  // namespace p3a
-}  // namespace request_otr
+}  // namespace request_otr::p3a
diff --git a/components/request_otr/browser/request_otr_p3a_unittest.cc b/components/request_otr/browser/request_otr_p3a_unittest.cc
index aeaabfd9aba..1cc68f8b23e 100644
--- a/components/request_otr/browser/request_otr_p3a_unittest.cc
+++ b/components/request_otr/browser/request_otr_p3a_unittest.cc
@@ -13,8 +13,7 @@
 #include "content/public/test/browser_task_environment.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
-namespace request_otr {
-namespace p3a {
+namespace request_otr::p3a {
 
 class RequestOTRP3AUnitTest : public testing::Test {
  public:
@@ -102,5 +101,4 @@ TEST_F(RequestOTRP3AUnitTest, SessionCount) {
   histogram_tester_.ExpectTotalCount(kSessionCountHistogramName, 5);
 }
 
-}  // namespace p3a
-}  // namespace request_otr
+}  // namespace request_otr::p3a
diff --git a/components/request_otr/common/features.cc b/components/request_otr/common/features.cc
index ab77effc92a..86e4626dce3 100644
--- a/components/request_otr/common/features.cc
+++ b/components/request_otr/common/features.cc
@@ -7,8 +7,7 @@
 
 #include "base/feature_list.h"
 
-namespace request_otr {
-namespace features {
+namespace request_otr::features {
 
 // When enabled, Brave will block domains listed in the Brave-maintained
 // request-OTR ('off-the-record') list, or any server that responds with a
@@ -18,5 +17,4 @@ BASE_FEATURE(kBraveRequestOTRTab,
              "BraveRequestOTRTab",
              base::FEATURE_DISABLED_BY_DEFAULT);
 
-}  // namespace features
-}  // namespace request_otr
+}  // namespace request_otr::features
diff --git a/components/sidebar/browser/sidebar_p3a.cc b/components/sidebar/browser/sidebar_p3a.cc
index 6b44cc58a10..a23cc5eb57b 100644
--- a/components/sidebar/browser/sidebar_p3a.cc
+++ b/components/sidebar/browser/sidebar_p3a.cc
@@ -13,8 +13,7 @@
 #include "brave/components/sidebar/common/features.h"
 #include "components/prefs/pref_service.h"
 
-namespace sidebar {
-namespace p3a {
+namespace sidebar::p3a {
 
 SidebarP3A::SidebarP3A(PrefService* profile_prefs)
     : profile_prefs_(profile_prefs) {
@@ -75,5 +74,4 @@ void SidebarP3A::RecordEnabledSetting(bool setting_changed) {
                                 setting_change_answer, 3);
 }
 
-}  // namespace p3a
-}  // namespace sidebar
+}  // namespace sidebar::p3a
diff --git a/components/skus/common/features.cc b/components/skus/common/features.cc
index 6bce0c045a8..491c6e80e0f 100644
--- a/components/skus/common/features.cc
+++ b/components/skus/common/features.cc
@@ -8,10 +8,8 @@
 #include "base/feature_list.h"
 #include "build/build_config.h"
 
-namespace skus {
-namespace features {
+namespace skus::features {
 
 BASE_FEATURE(kSkusFeature, "SkusFeature", base::FEATURE_ENABLED_BY_DEFAULT);
 
-}  // namespace features
-}  // namespace skus
+}  // namespace skus::features
diff --git a/mojo/brave_ast_patcher/brave_ast_patcher_unittest.cc b/mojo/brave_ast_patcher/brave_ast_patcher_unittest.cc
index da25eb8ef37..2010eddff4f 100644
--- a/mojo/brave_ast_patcher/brave_ast_patcher_unittest.cc
+++ b/mojo/brave_ast_patcher/brave_ast_patcher_unittest.cc
@@ -11,8 +11,7 @@
 // This file contains patched mojom usage to ensure that all new definitions,
 // values and members are properly added using the patching mechanism.
 
-namespace brave_ast_patcher {
-namespace mojom {
+namespace brave_ast_patcher::mojom {
 
 // Create interface implementations to ensure new methods exist and are
 // overridable.
@@ -145,5 +144,4 @@ TEST(BraveAstPatcherTest, InterfaceInstantiations) {
   NewGlobalInterfaceImpl new_global_interface_impl;
 }
 
-}  // namespace mojom
-}  // namespace brave_ast_patcher
+}  // namespace brave_ast_patcher::mojom
diff --git a/vendor/brave_base/random.cc b/vendor/brave_base/random.cc
index 3c178914268..a4ed4217740 100644
--- a/vendor/brave_base/random.cc
+++ b/vendor/brave_base/random.cc
@@ -11,8 +11,7 @@
 #include "base/bits.h"
 #include "crypto/random.h"
 
-namespace brave_base {
-namespace random {
+namespace brave_base::random {
 
 uint64_t Uniform64() {
   uint64_t x;
@@ -120,5 +119,4 @@ double Uniform_01(uint64_t e, uint64_t u) {
 
 }  // namespace deterministic
 
-}  // namespace random
-}  // namespace brave_base
+}  // namespace brave_base::random