diff --git a/fastapi/routing.py b/fastapi/routing.py
index ac5e19d99835a..cf3f98917cf6d 100644
--- a/fastapi/routing.py
+++ b/fastapi/routing.py
@@ -581,7 +581,7 @@ def add_api_websocket_route(
         self, path: str, endpoint: Callable[..., Any], name: Optional[str] = None
     ) -> None:
         route = APIWebSocketRoute(
-            path,
+            self.prefix + path,
             endpoint=endpoint,
             name=name,
             dependency_overrides_provider=self.dependency_overrides_provider,