diff --git a/gma/src/include/firebase/gma.h b/gma/src/include/firebase/gma.h
index eca1666a6a..002bbf8125 100644
--- a/gma/src/include/firebase/gma.h
+++ b/gma/src/include/firebase/gma.h
@@ -61,6 +61,9 @@ class Future {
 ///
 /// The GMA API allows you to load and display mobile ads using the Google
 /// Mobile Ads SDK. Each ad format has its own header file.
+///
+/// @deprecated The Google Mobile Ads C++ SDK is now deprecated. Please see
+/// https://developers.google.com/admob/cpp/sdk for more information.
 namespace gma {
 
 /// Initializes Google Mobile Ads (GMA) via Firebase.
@@ -78,7 +81,10 @@ namespace gma {
 /// @return If init_result_out is kInitResultSuccess, this Future will contain
 /// the initialization status of each adapter once initialization is complete.
 /// Otherwise, the returned Future will have kFutureStatusInvalid.
-Future<AdapterInitializationStatus> Initialize(
+///
+/// @deprecated The Google Mobile Ads C++ SDK is now deprecated. Please see
+/// https://developers.google.com/admob/cpp/sdk for more information.
+FIREBASE_DEPRECATED Future<AdapterInitializationStatus> Initialize(
     const ::firebase::App& app, InitResult* init_result_out = nullptr);
 
 #if FIREBASE_PLATFORM_ANDROID || defined(DOXYGEN)
@@ -107,7 +113,10 @@ Future<AdapterInitializationStatus> Initialize(
 /// @return If init_result_out is kInitResultSuccess, this Future will contain
 /// the initialization status of each adapter once initialization is complete.
 /// Otherwise, the returned Future will have kFutureStatusInvalid.
-Future<AdapterInitializationStatus> Initialize(
+///
+/// @deprecated The Google Mobile Ads C++ SDK is now deprecated. Please see
+/// https://developers.google.com/admob/cpp/sdk for more information.
+FIREBASE_DEPRECATED Future<AdapterInitializationStatus> Initialize(
     JNIEnv* jni_env, jobject activity, InitResult* init_result_out = nullptr);
 
 #endif  // defined(__ANDROID__) || defined(DOXYGEN)
@@ -126,7 +135,10 @@ Future<AdapterInitializationStatus> Initialize(
 /// will contain the initialization status of each adapter once initialization
 /// is complete. Otherwise, the returned Future will have
 /// <code>kFutureStatusInvalid</code>.
-Future<AdapterInitializationStatus> Initialize(
+///
+/// @deprecated The Google Mobile Ads C++ SDK is now deprecated. Please see
+/// https://developers.google.com/admob/cpp/sdk for more information.
+FIREBASE_DEPRECATED Future<AdapterInitializationStatus> Initialize(
     InitResult* init_result_out = nullptr);
 #endif  // !defined(__ANDROID__) || defined(DOXYGEN)
 
diff --git a/gma/src/include/firebase/gma/ad_view.h b/gma/src/include/firebase/gma/ad_view.h
index b2a1cba24d..a935e38ba1 100644
--- a/gma/src/include/firebase/gma/ad_view.h
+++ b/gma/src/include/firebase/gma/ad_view.h
@@ -63,6 +63,9 @@ struct BoundingBox;
 ///   ad_view->LoadAd(your_ad_request);
 /// }
 /// @endcode
+///
+/// @deprecated The Google Mobile Ads C++ SDK is now deprecated. Please see
+/// https://developers.google.com/admob/cpp/sdk for more information.
 class AdView {
  public:
   /// The possible screen positions for a @ref AdView, configured via
@@ -86,7 +89,7 @@ class AdView {
 
   /// Creates an uninitialized @ref AdView object.
   /// @ref Initialize must be called before the object is used.
-  AdView();
+  FIREBASE_DEPRECATED AdView();
 
   ~AdView();
 
@@ -94,12 +97,13 @@ class AdView {
   /// @param[in] parent The platform-specific UI element that will host the ad.
   /// @param[in] ad_unit_id The ad unit ID to use when requesting ads.
   /// @param[in] size The desired ad size for the ad.
-  Future<void> Initialize(AdParent parent, const char* ad_unit_id,
-                          const AdSize& size);
+  FIREBASE_DEPRECATED Future<void> Initialize(AdParent parent,
+                                              const char* ad_unit_id,
+                                              const AdSize& size);
 
   /// Returns a @ref Future that has the status of the last call to
   /// @ref Initialize.
-  Future<void> InitializeLastResult() const;
+  FIREBASE_DEPRECATED Future<void> InitializeLastResult() const;
 
   /// Begins an asynchronous request for an ad. If successful, the ad will
   /// automatically be displayed in the AdView.
diff --git a/gma/src/include/firebase/gma/interstitial_ad.h b/gma/src/include/firebase/gma/interstitial_ad.h
index 4680537178..8db7acfd28 100644
--- a/gma/src/include/firebase/gma/interstitial_ad.h
+++ b/gma/src/include/firebase/gma/interstitial_ad.h
@@ -69,21 +69,24 @@ class InterstitialAdInternal;
 ///   interstitial->Show();
 /// }
 /// @endcode
+///
+/// @deprecated The Google Mobile Ads C++ SDK is now deprecated. Please see
+/// https://developers.google.com/admob/cpp/sdk for more information.
 class InterstitialAd {
  public:
   /// Creates an uninitialized @ref InterstitialAd object.
   /// @ref Initialize must be called before the object is used.
-  InterstitialAd();
+  FIREBASE_DEPRECATED InterstitialAd();
 
   ~InterstitialAd();
 
   /// Initialize the @ref InterstitialAd object.
   /// @param[in] parent The platform-specific UI element that will host the ad.
-  Future<void> Initialize(AdParent parent);
+  FIREBASE_DEPRECATED Future<void> Initialize(AdParent parent);
 
   /// Returns a @ref Future containing the status of the last call to
   /// @ref Initialize.
-  Future<void> InitializeLastResult() const;
+  FIREBASE_DEPRECATED Future<void> InitializeLastResult() const;
 
   /// Begins an asynchronous request for an ad.
   ///
diff --git a/gma/src/include/firebase/gma/rewarded_ad.h b/gma/src/include/firebase/gma/rewarded_ad.h
index a3c5431486..e2bf38a3e3 100644
--- a/gma/src/include/firebase/gma/rewarded_ad.h
+++ b/gma/src/include/firebase/gma/rewarded_ad.h
@@ -71,6 +71,9 @@ class RewardedAdInternal;
 ///   rewarded->Show(&my_user_earned_reward_listener);
 /// }
 /// @endcode
+///
+/// @deprecated The Google Mobile Ads C++ SDK is now deprecated. Please see
+/// https://developers.google.com/admob/cpp/sdk for more information.
 class RewardedAd {
  public:
   /// Options for RewardedAd server-side verification callbacks. Set options on
@@ -86,17 +89,17 @@ class RewardedAd {
 
   /// Creates an uninitialized @ref RewardedAd object.
   /// @ref Initialize must be called before the object is used.
-  RewardedAd();
+  FIREBASE_DEPRECATED RewardedAd();
 
   ~RewardedAd();
 
   /// Initialize the @ref RewardedAd object.
   /// @param[in] parent The platform-specific UI element that will host the ad.
-  Future<void> Initialize(AdParent parent);
+  FIREBASE_DEPRECATED Future<void> Initialize(AdParent parent);
 
   /// Returns a @ref Future containing the status of the last call to
   /// @ref Initialize.
-  Future<void> InitializeLastResult() const;
+  FIREBASE_DEPRECATED Future<void> InitializeLastResult() const;
 
   /// Begins an asynchronous request for an ad.
   ///
diff --git a/release_build_files/readme.md b/release_build_files/readme.md
index 9c7cdfe443..fb162b26ec 100644
--- a/release_build_files/readme.md
+++ b/release_build_files/readme.md
@@ -638,7 +638,9 @@ code.
     - Analytics (iOS): Add support for
       `InitiateOnDeviceConversionMeasurementWithHashedEmailAddress` and
       `InitiateOnDeviceConversionMeasurementWithHashedPhoneNumber`.
-    - Messaging (Android): Addressed potential race condition on receiving
+    - GMA: The GMA C++ SDK is now deprecated. For more information, see the
+      [SDK documentation](https://developers.google.com/admob/cpp/sdk).
+    - Messaging (Android): Fixed a potential race condition on receiving
       messages after cleanup.
 
 ### 12.0.0