--- a/chrome/browser/extensions/chrome_browser_context_keyed_service_factories.cc
+++ b/chrome/browser/extensions/chrome_browser_context_keyed_service_factories.cc
@@ -22,7 +22,6 @@
 #include "chrome/browser/extensions/extension_web_ui_override_registrar.h"
 #include "chrome/browser/extensions/install_tracker_factory.h"
 #include "chrome/browser/extensions/install_verifier_factory.h"
-#include "chrome/browser/extensions/manifest_v2_experiment_manager.h"
 #include "chrome/browser/extensions/menu_manager_factory.h"
 #include "chrome/browser/extensions/permissions/permissions_updater.h"
 #include "chrome/browser/extensions/plugin_manager.h"
@@ -48,7 +47,6 @@ void EnsureChromeBrowserContextKeyedServ
   extensions::IncognitoConnectability::EnsureFactoryBuilt();
   extensions::InstallTrackerFactory::GetInstance();
   extensions::InstallVerifierFactory::GetInstance();
-  extensions::ManifestV2ExperimentManager::GetFactory();
   extensions::MenuManagerFactory::GetInstance();
   extensions::PermissionsUpdater::EnsureAssociatedFactoryBuilt();
 #if BUILDFLAG(ENABLE_PLUGINS)
--- a/chrome/browser/extensions/extension_management.cc
+++ b/chrome/browser/extensions/extension_management.cc
@@ -287,31 +287,7 @@ bool ExtensionManagement::IsAllowedManif
     int manifest_version,
     const std::string& extension_id,
     Manifest::Type manifest_type) {
-  bool enabled_by_default =
-      !base::FeatureList::IsEnabled(
-          extensions_features::kExtensionsManifestV3Only) ||
-      manifest_version >= 3;
-
-  // Manifest version policy only supports normal extensions and Chrome OS login
-  // screen extension.
-  if (manifest_type != Manifest::Type::TYPE_EXTENSION &&
-      manifest_type != Manifest::Type::TYPE_LOGIN_SCREEN_EXTENSION) {
-    return enabled_by_default;
-  }
-  switch (global_settings_->manifest_v2_setting) {
-    case internal::GlobalSettings::ManifestV2Setting::kDefault:
-      return enabled_by_default;
-    case internal::GlobalSettings::ManifestV2Setting::kDisabled:
-      return manifest_version >= 3;
-    case internal::GlobalSettings::ManifestV2Setting::kEnabled:
       return true;
-    case internal::GlobalSettings::ManifestV2Setting::kEnabledForForceInstalled:
-      auto installation_mode =
-          GetInstallationMode(extension_id, /*update_url=*/std::string());
-      return manifest_version >= 3 ||
-             installation_mode == INSTALLATION_FORCED ||
-             installation_mode == INSTALLATION_RECOMMENDED;
-  }
 }
 
 bool ExtensionManagement::IsAllowedManifestVersion(const Extension* extension) {
@@ -332,26 +308,8 @@ bool ExtensionManagement::IsExemptFromMV
     return false;
   }
 
-  switch (global_settings_->manifest_v2_setting) {
-    case internal::GlobalSettings::ManifestV2Setting::kDefault:
-      // Default browser behavior. Not exempt.
-      return false;
-    case internal::GlobalSettings::ManifestV2Setting::kDisabled:
-      // All MV2 extensions are disallowed. Not exempt.
-      return false;
-    case internal::GlobalSettings::ManifestV2Setting::kEnabled:
       // All MV2 extensions are allowed. Exempt.
       return true;
-    case internal::GlobalSettings::ManifestV2Setting::kEnabledForForceInstalled:
-      // Force-installed MV2 extensions are allowed. Exempt if it's a force-
-      // installed extension only.
-      auto installation_mode =
-          GetInstallationMode(extension_id, /*update_url=*/std::string());
-      return installation_mode == INSTALLATION_FORCED ||
-             installation_mode == INSTALLATION_RECOMMENDED;
-  }
-
-  return false;
 }
 
 bool ExtensionManagement::IsAllowedByUnpublishedAvailabilityPolicy(
--- a/chrome/browser/extensions/manifest_v2_experiment_manager.cc
+++ b/chrome/browser/extensions/manifest_v2_experiment_manager.cc
@@ -76,11 +76,6 @@ KeyedService* ManifestV2ExperimentManage
 }
 
 MV2ExperimentStage CalculateCurrentExperimentStage() {
-  if (base::FeatureList::IsEnabled(
-          extensions_features::kExtensionManifestV2DeprecationWarning)) {
-    return MV2ExperimentStage::kWarning;
-  }
-
   return MV2ExperimentStage::kNone;
 }
 
