diff --git a/media/audio/win/audio_ducker_win.cc b/media/audio/win/audio_ducker_win.cc
index 0afab9a6eb4f5..def972f78512c 100644
--- a/media/audio/win/audio_ducker_win.cc
+++ b/media/audio/win/audio_ducker_win.cc
@@ -121,13 +121,13 @@ void AudioDuckerWin::StartDuckingOtherWindowsApplications() {
 
   if (!session_creation_observer_) {
     session_creation_observer_ =
-        std::make_unique<AudioSessionCreationObserverWin>(
+        Microsoft::WRL::Make<AudioSessionCreationObserverWin>(
             base::BindPostTaskToCurrentDefault(base::BindRepeating(
                 &AudioDuckerWin::DuckNewAudioSessionsIfNecessary,
                 weak_factory_.GetWeakPtr())));
   }
   ducked_audio_session_manager_->RegisterSessionNotification(
-      session_creation_observer_.get());
+      session_creation_observer_.Get());
 
   // `base::Unretained()` is safe here because this callback is called
   // synchronously.
@@ -151,7 +151,7 @@ void AudioDuckerWin::StopDuckingOtherWindowsApplications() {
     if (ducked_audio_session_manager_) {
       CHECK(session_creation_observer_);
       ducked_audio_session_manager_->UnregisterSessionNotification(
-          session_creation_observer_.get());
+          session_creation_observer_.Get());
       ducked_audio_session_manager_.Reset();
     }
     return;
@@ -174,7 +174,7 @@ void AudioDuckerWin::StopDuckingOtherWindowsApplications() {
 
   ducked_applications_.clear();
   ducked_audio_session_manager_->UnregisterSessionNotification(
-      session_creation_observer_.get());
+      session_creation_observer_.Get());
   ducked_audio_session_manager_.Reset();
 }
 
diff --git a/media/audio/win/audio_ducker_win.h b/media/audio/win/audio_ducker_win.h
index 691dc5e86f9ad..988f166774993 100644
--- a/media/audio/win/audio_ducker_win.h
+++ b/media/audio/win/audio_ducker_win.h
@@ -57,8 +57,12 @@ class MEDIA_EXPORT AudioDuckerWin {
   // Called when the system notifies us of a new audio session being created.
   void DuckNewAudioSessionsIfNecessary();
 
-  // Listens for audio session creation notifications from the OS.
-  std::unique_ptr<AudioSessionCreationObserverWin> session_creation_observer_;
+  // Listens for audio session creation notifications from the OS. Held via
+  // ComPtr (not unique_ptr) because Windows' CAudioSessionManager also holds a
+  // COM reference for the duration of in-flight OnSessionCreated() callbacks on
+  // the MM thread; the object must outlive both owners.
+  Microsoft::WRL::ComPtr<AudioSessionCreationObserverWin>
+      session_creation_observer_;
 
   // Used to determine which applications we should duck.
   ShouldDuckProcessCallback should_duck_process_callback_;
diff --git a/media/audio/win/audio_session_creation_observer_win.cc b/media/audio/win/audio_session_creation_observer_win.cc
index 4fdf90e2dfed1..3df84ef3219d8 100644
--- a/media/audio/win/audio_session_creation_observer_win.cc
+++ b/media/audio/win/audio_session_creation_observer_win.cc
@@ -16,25 +16,6 @@ AudioSessionCreationObserverWin::AudioSessionCreationObserverWin(
 
 AudioSessionCreationObserverWin::~AudioSessionCreationObserverWin() = default;
 
-ULONG AudioSessionCreationObserverWin::AddRef() {
-  return 1;
-}
-
-ULONG AudioSessionCreationObserverWin::Release() {
-  return 1;
-}
-
-HRESULT AudioSessionCreationObserverWin::QueryInterface(REFIID iid,
-                                                        void** object) {
-  if (iid == IID_IUnknown || iid == __uuidof(IAudioSessionNotification)) {
-    *object = static_cast<IAudioSessionNotification*>(this);
-    return S_OK;
-  }
-
-  *object = nullptr;
-  return E_NOINTERFACE;
-}
-
 HRESULT AudioSessionCreationObserverWin::OnSessionCreated(
     IAudioSessionControl* session) {
   session_created_cb_.Run();
diff --git a/media/audio/win/audio_session_creation_observer_win.h b/media/audio/win/audio_session_creation_observer_win.h
index 54982dfdf635a..73a3a25a1d7bb 100644
--- a/media/audio/win/audio_session_creation_observer_win.h
+++ b/media/audio/win/audio_session_creation_observer_win.h
@@ -6,6 +6,8 @@
 #define MEDIA_AUDIO_WIN_AUDIO_SESSION_CREATION_OBSERVER_WIN_H_
 
 #include <audiopolicy.h>
+#include <wrl/client.h>
+#include <wrl/implements.h>
 
 #include "base/functional/callback.h"
 
@@ -13,7 +15,18 @@ namespace media {
 
 // Calls the given callback when notified by the IAudioSessionManager2 that an
 // audio session was created.
-class AudioSessionCreationObserverWin : public IAudioSessionNotification {
+//
+// Uses WRL::RuntimeClass so that AddRef()/Release() perform real COM
+// refcounting. Windows' CAudioSessionManager AddRef()s registered notification
+// clients for the duration of an in-flight OnSessionCreated() dispatch on the
+// MM thread; with stubbed refcounting the object could be freed underneath an
+// in-flight callback. Owners must hold this via Microsoft::WRL::ComPtr (created
+// with Microsoft::WRL::Make<>) so the object survives until both Chromium and
+// Windows have released their references.
+class AudioSessionCreationObserverWin
+    : public Microsoft::WRL::RuntimeClass<
+          Microsoft::WRL::RuntimeClassFlags<Microsoft::WRL::ClassicCom>,
+          IAudioSessionNotification> {
  public:
   // `session_created_callback` is called when the system notifies us of a new
   // audio session via `OnSessionCreated()`.
@@ -23,12 +36,9 @@ class AudioSessionCreationObserverWin : public IAudioSessionNotification {
       delete;
   AudioSessionCreationObserverWin& operator=(
       const AudioSessionCreationObserverWin&) = delete;
-  virtual ~AudioSessionCreationObserverWin();
+  ~AudioSessionCreationObserverWin() override;
 
   // IAudioSessionNotification:
-  IFACEMETHODIMP_(ULONG) AddRef() override;
-  IFACEMETHODIMP_(ULONG) Release() override;
-  IFACEMETHODIMP QueryInterface(REFIID iid, void** object) override;
   IFACEMETHODIMP OnSessionCreated(IAudioSessionControl* session) override;
 
  private: