diff --git a/browser/brave_app_controller_mac.h b/browser/brave_app_controller_mac.h
index b0e29b28c00..a5860351f52 100644
--- a/browser/brave_app_controller_mac.h
+++ b/browser/brave_app_controller_mac.h
@@ -8,11 +8,15 @@
 
 #import <Cocoa/Cocoa.h>
 
+#import "brave/components/brave_origin/buildflags/buildflags.h"
 #import "chrome/browser/app_controller_mac.h"
 
 // * Manages logic to switch hotkey between copy and copy clean link item.
 // * Add "New Private Window with Tor" to the dock menu.
 @interface BraveAppController : AppController
+#if BUILDFLAG(IS_BRAVE_ORIGIN_BRANDED)
+- (void)restoreProfileMenu;
+#endif
 @end
 
 #endif  // BRAVE_BROWSER_BRAVE_APP_CONTROLLER_MAC_H_
diff --git a/browser/brave_app_controller_mac.mm b/browser/brave_app_controller_mac.mm
index 8d1c161e23c..784eb8df17a 100644
--- a/browser/brave_app_controller_mac.mm
+++ b/browser/brave_app_controller_mac.mm
@@ -87,6 +87,11 @@ class TorPrefObserver : public BooleanPrefMember {
   NSMenuItem* _copyMenuItem;
   NSMenuItem* _copyCleanLinkMenuItem;
 
+#if BUILDFLAG(IS_BRAVE_ORIGIN_BRANDED)
+  NSMenuItem* _profileMenuItem;  // Stashed while startup dialog is showing
+  NSInteger _profileMenuIndex;   // Original position in the menu bar
+#endif
+
 #if BUILDFLAG(ENABLE_TOR)
   NSMenuItem* _torMenuItem;      // For dock menu
   NSMenuItem* _torMainMenuItem;  // For main menu
@@ -96,6 +101,14 @@ class TorPrefObserver : public BooleanPrefMember {
 }
 @end
 
+#if BUILDFLAG(IS_BRAVE_ORIGIN_BRANDED)
+void BraveRestoreProfileMenu() {
+  auto* controller =
+      static_cast<BraveAppController*>(AppController.sharedController);
+  [controller restoreProfileMenu];
+}
+#endif
+
 @implementation BraveAppController
 
 #if BUILDFLAG(IS_BRAVE_ORIGIN_BRANDED)
@@ -132,11 +145,41 @@ class TorPrefObserver : public BooleanPrefMember {
   return [super applicationShouldHandleReopen:theApplication
                             hasVisibleWindows:hasVisibleWindows];
 }
+
+- (void)application:(NSApplication*)sender openURLs:(NSArray<NSURL*>*)urls {
+  if (BraveOriginStartupView::IsShowing()) {
+    return;
+  }
+  [super application:sender openURLs:urls];
+}
+
+- (void)restoreProfileMenu {
+  if (_profileMenuItem) {
+    [[NSApp mainMenu] insertItem:_profileMenuItem atIndex:_profileMenuIndex];
+    _profileMenuItem = nil;
+  }
+}
 #endif  // BUILDFLAG(IS_BRAVE_ORIGIN_BRANDED)
 
 - (void)mainMenuCreated {
   [super mainMenuCreated];
 
+#if BUILDFLAG(IS_BRAVE_ORIGIN_BRANDED)
+  // Stash and remove the Profiles top-level menu. Profile switching, "Manage",
+  // and "Add Profile" all open browser windows that bypass the startup dialog.
+  // restoreProfileMenu re-inserts it. It is called from the startup completion
+  // callback, or immediately if no dialog is needed.
+  {
+    NSMenu* mainMenu = [NSApp mainMenu];
+    NSMenuItem* profileMenu = [mainMenu itemWithTag:IDC_PROFILE_MAIN_MENU];
+    if (profileMenu) {
+      _profileMenuIndex = [mainMenu indexOfItem:profileMenu];
+      _profileMenuItem = profileMenu;
+      [mainMenu removeItem:profileMenu];
+    }
+  }
+#endif  // BUILDFLAG(IS_BRAVE_ORIGIN_BRANDED)
+
   NSMenu* editMenu = [[[NSApp mainMenu] itemWithTag:IDC_EDIT_MENU] submenu];
   _copyMenuItem = [editMenu itemWithTag:IDC_CONTENT_CONTEXT_COPY];
   DCHECK(_copyMenuItem);
@@ -302,6 +345,14 @@ class TorPrefObserver : public BooleanPrefMember {
 }
 
 - (NSMenu*)applicationDockMenu:(NSApplication*)sender {
+#if BUILDFLAG(IS_BRAVE_ORIGIN_BRANDED)
+  if (BraveOriginStartupView::IsShowing()) {
+    // Return an empty dock menu while the startup dialog is showing.
+    // The system always adds "Quit" automatically.
+    return [[NSMenu alloc] initWithTitle:@""];
+  }
+#endif  // BUILDFLAG(IS_BRAVE_ORIGIN_BRANDED)
+
   auto* menu = [super applicationDockMenu:sender];
 
 #if BUILDFLAG(ENABLE_TOR)
diff --git a/chromium_src/chrome/browser/ui/startup/startup_browser_creator.cc b/chromium_src/chrome/browser/ui/startup/startup_browser_creator.cc
index 899949a4f95..a5e5357a46e 100644
--- a/chromium_src/chrome/browser/ui/startup/startup_browser_creator.cc
+++ b/chromium_src/chrome/browser/ui/startup/startup_browser_creator.cc
@@ -23,6 +23,11 @@
 #include "chrome/browser/platform_util.h"
 #include "chrome/browser/profiles/profile_manager.h"
 #include "components/prefs/pref_service.h"
+#if BUILDFLAG(IS_MAC)
+// Defined in brave_app_controller_mac.mm. We can't include the ObjC header
+// from a .cc file, so declare the free function directly.
+void BraveRestoreProfileMenu();
+#endif
 #endif
 
 #ifdef LaunchModeRecorder
@@ -154,6 +159,11 @@ bool StartupBrowserCreator::Start(const base::CommandLine& cmd_line,
                const base::CommandLine& cmd_line, const base::FilePath& cur_dir,
                StartupProfileInfo profile_info,
                const Profiles& last_opened_profiles) {
+#if BUILDFLAG(IS_MAC)
+              // Re-insert the Profiles menu that was stashed while the
+              // startup dialog was showing.
+              BraveRestoreProfileMenu();
+#endif
               StartupBrowserCreator browser_creator;
               browser_creator.AddFirstRunTabs(first_run_tabs);
               browser_creator.Start_ChromiumImpl(cmd_line, cur_dir,
@@ -165,6 +175,10 @@ bool StartupBrowserCreator::Start(const base::CommandLine& cmd_line,
         std::make_unique<StartupDialogDelegate>());
     return true;
   }
+#if BUILDFLAG(IS_MAC)
+  // No dialog needed, restore the Profiles menu immediately.
+  BraveRestoreProfileMenu();
+#endif
 #endif  // BUILDFLAG(IS_BRAVE_ORIGIN_BRANDED)
   return Start_ChromiumImpl(cmd_line, cur_dir, std::move(profile_info),
                             last_opened_profiles);