diff --git a/CHANGES/4174.bugfix b/CHANGES/4174.bugfix
new file mode 100644
index 00000000000..82c37e4edbc
--- /dev/null
+++ b/CHANGES/4174.bugfix
@@ -0,0 +1 @@
+Preserve handler function attributes for the case of subapps
diff --git a/aiohttp/web_app.py b/aiohttp/web_app.py
index 90915d2b9c9..8ce59b1748b 100644
--- a/aiohttp/web_app.py
+++ b/aiohttp/web_app.py
@@ -1,7 +1,7 @@
 import asyncio
 import logging
 import warnings
-from functools import partial
+from functools import partial, update_wrapper
 from typing import (  # noqa
     TYPE_CHECKING,
     Any,
@@ -325,7 +325,9 @@ async def _handle(self, request: Request) -> StreamResponse:
                 for app in match_info.apps[::-1]:
                     assert app.pre_frozen, "middleware handlers are not ready"
                     for m in app._middlewares_handlers:  # noqa
-                        handler = partial(m, handler=handler)
+                        handler = update_wrapper(
+                            partial(m, handler=handler), handler
+                        )
 
             resp = await handler(request)