diff --git a/changelog.d/13843.misc b/changelog.d/13843.misc
new file mode 100644
index 000000000000..f6caaa889566
--- /dev/null
+++ b/changelog.d/13843.misc
@@ -0,0 +1 @@
+Remove the `complete_sso_login` method from the Module API which was deprecated in Synapse 1.13.0.
diff --git a/synapse/handlers/auth.py b/synapse/handlers/auth.py
index 0327fc57a4ec..84bf73270252 100644
--- a/synapse/handlers/auth.py
+++ b/synapse/handlers/auth.py
@@ -1687,41 +1687,10 @@ async def complete_sso_login(
             respond_with_html(request, 403, self._sso_account_deactivated_template)
             return
 
-        profile = await self.store.get_profileinfo(
+        user_profile_data = await self.store.get_profileinfo(
             UserID.from_string(registered_user_id).localpart
         )
 
-        self._complete_sso_login(
-            registered_user_id,
-            auth_provider_id,
-            request,
-            client_redirect_url,
-            extra_attributes,
-            new_user=new_user,
-            user_profile_data=profile,
-            auth_provider_session_id=auth_provider_session_id,
-        )
-
-    def _complete_sso_login(
-        self,
-        registered_user_id: str,
-        auth_provider_id: str,
-        request: Request,
-        client_redirect_url: str,
-        extra_attributes: Optional[JsonDict] = None,
-        new_user: bool = False,
-        user_profile_data: Optional[ProfileInfo] = None,
-        auth_provider_session_id: Optional[str] = None,
-    ) -> None:
-        """
-        The synchronous portion of complete_sso_login.
-
-        This exists purely for backwards compatibility of synapse.module_api.ModuleApi.
-        """
-
-        if user_profile_data is None:
-            user_profile_data = ProfileInfo(None, None)
-
         # Store any extra attributes which will be passed in the login response.
         # Note that this is per-user so it may overwrite a previous value, this
         # is considered OK since the newest SSO attributes should be most valid.
diff --git a/synapse/module_api/__init__.py b/synapse/module_api/__init__.py
index 87ba154cb737..805ba47d32da 100644
--- a/synapse/module_api/__init__.py
+++ b/synapse/module_api/__init__.py
@@ -843,7 +843,7 @@ def complete_sso_login(
         want their access token sent to `client_redirect_url`, or redirect them to that
         URL with a token directly if the URL matches with one of the whitelisted clients.
 
-        This is deprecated in favor of complete_sso_login_async.
+        This was removed in favor of complete_sso_login_async in Synapse 1.68.0.
 
         Added in Synapse v1.11.1.
 
@@ -854,11 +854,8 @@ def complete_sso_login(
             client_redirect_url: The URL to which to offer to redirect the user (or to
                 redirect them directly if whitelisted).
         """
-        self._auth_handler._complete_sso_login(
-            registered_user_id,
-            "<unknown>",
-            request,
-            client_redirect_url,
+        raise Exception(
+            "ModuleApi.complete_sso_login is deprecated in favor of ModuleApi.complete_sso_login_async"
         )
 
     async def complete_sso_login_async(