diff --git a/quick_check.py b/quick_check.py
new file mode 100644
index 00000000..e69de29b
diff --git a/src/supabase/src/supabase/_async/client.py b/src/supabase/src/supabase/_async/client.py
index 8b81e6ed..a43885b1 100644
--- a/src/supabase/src/supabase/_async/client.py
+++ b/src/supabase/src/supabase/_async/client.py
@@ -97,6 +97,7 @@ def __init__(
         self._postgrest: Optional[AsyncPostgrestClient] = None
         self._storage: Optional[AsyncStorageClient] = None
         self._functions: Optional[AsyncFunctionsClient] = None
+        self.auth.admin._headers = {**self.auth.admin._headers}
         self.auth.on_auth_state_change(self._listen_to_auth_events)
 
     @classmethod
@@ -342,12 +343,13 @@ def _listen_to_auth_events(
             self._storage = None
             self._functions = None
             access_token = session.access_token if session else self.supabase_key
+
         auth_header = self._create_auth_header(access_token)
         self.options.headers["Authorization"] = auth_header
         self.auth._headers["Authorization"] = auth_header
+        self.auth.admin._headers["Authorization"] = self._create_auth_header(self.supabase_key)
         asyncio.create_task(self.realtime.set_auth(access_token))
 
-
 async def create_client(
     supabase_url: str,
     supabase_key: str,
diff --git a/src/supabase/src/supabase/_sync/client.py b/src/supabase/src/supabase/_sync/client.py
index 29c0246b..9f81dcc7 100644
--- a/src/supabase/src/supabase/_sync/client.py
+++ b/src/supabase/src/supabase/_sync/client.py
@@ -96,6 +96,7 @@ def __init__(
         self._postgrest: Optional[SyncPostgrestClient] = None
         self._storage: Optional[SyncStorageClient] = None
         self._functions: Optional[SyncFunctionsClient] = None
+        self.auth.admin._headers = {**self.auth.admin._headers}
         self.auth.on_auth_state_change(self._listen_to_auth_events)
 
     @classmethod
@@ -344,6 +345,7 @@ def _listen_to_auth_events(
         auth_header = self._create_auth_header(access_token)
         self.options.headers["Authorization"] = auth_header
         self.auth._headers["Authorization"] = auth_header
+        self.auth.admin._headers["Authorization"] = self._create_auth_header(self.supabase_key)
 
 
 def create_client(
diff --git a/src/supabase/tests/_sync/test_client.py b/src/supabase/tests/_sync/test_client.py
index a490d67d..ba60a881 100644
--- a/src/supabase/tests/_sync/test_client.py
+++ b/src/supabase/tests/_sync/test_client.py
@@ -282,3 +282,24 @@ def test_httpx_client_base_url_isolation() -> None:
     assert str(postgrest.base_url).rstrip("/").endswith("/rest/v1"), (
         "PostgREST base_url was mutated after accessing functions"
     )
+
+def test_admin_authorization_header_not_overwritten_on_auth_events() -> None:
+    """Admin API should always use the supabase_key, never the user session token.
+    Regression test for https://github.com/supabase/supabase-py/issues/1404
+    """
+    url = os.environ["SUPABASE_TEST_URL"]
+    key = os.environ["SUPABASE_TEST_KEY"]
+
+    client = create_client(url, key)
+
+    mock_session = MagicMock(access_token="secretuserjwt")
+    realtime_mock = Mock()
+    client.realtime = realtime_mock
+
+    client._listen_to_auth_events("SIGNED_IN", mock_session)
+
+    # auth._headers should have the user token (existing behaviour)
+    assert client.auth._headers.get("Authorization") == "Bearer secretuserjwt"
+
+    # admin._headers must always keep the original supabase_key
+    assert client.auth.admin._headers.get("Authorization") == f"Bearer {key}"
diff --git a/test_bug.py b/test_bug.py
new file mode 100644
index 00000000..e69de29b