diff --git a/CHANGES/10422.misc.rst b/CHANGES/10422.misc.rst
new file mode 100644
index 00000000000..7ecb1c0e2e2
--- /dev/null
+++ b/CHANGES/10422.misc.rst
@@ -0,0 +1,3 @@
+Added human-readable error messages to the exceptions for WebSocket disconnects due to PONG not being received -- by :user:`bdraco`.
+
+Previously, the error messages were empty strings, which made it hard to determine what went wrong.
diff --git a/aiohttp/client_ws.py b/aiohttp/client_ws.py
index f4cfa1bffe8..daa57d1930b 100644
--- a/aiohttp/client_ws.py
+++ b/aiohttp/client_ws.py
@@ -163,7 +163,9 @@ def _ping_task_done(self, task: "asyncio.Task[None]") -> None:
         self._ping_task = None
 
     def _pong_not_received(self) -> None:
-        self._handle_ping_pong_exception(ServerTimeoutError())
+        self._handle_ping_pong_exception(
+            ServerTimeoutError(f"No PONG received after {self._pong_heartbeat} seconds")
+        )
 
     def _handle_ping_pong_exception(self, exc: BaseException) -> None:
         """Handle exceptions raised during ping/pong processing."""
diff --git a/aiohttp/web_ws.py b/aiohttp/web_ws.py
index 0fb1549a3aa..a448bca101e 100644
--- a/aiohttp/web_ws.py
+++ b/aiohttp/web_ws.py
@@ -182,7 +182,11 @@ def _ping_task_done(self, task: "asyncio.Task[None]") -> None:
 
     def _pong_not_received(self) -> None:
         if self._req is not None and self._req.transport is not None:
-            self._handle_ping_pong_exception(asyncio.TimeoutError())
+            self._handle_ping_pong_exception(
+                asyncio.TimeoutError(
+                    f"No PONG received after {self._pong_heartbeat} seconds"
+                )
+            )
 
     def _handle_ping_pong_exception(self, exc: BaseException) -> None:
         """Handle exceptions raised during ping/pong processing."""
diff --git a/tests/test_client_ws_functional.py b/tests/test_client_ws_functional.py
index 7ede7432adf..54cd5e92f80 100644
--- a/tests/test_client_ws_functional.py
+++ b/tests/test_client_ws_functional.py
@@ -902,6 +902,7 @@ async def handler(request):
         assert resp.close_code is WSCloseCode.ABNORMAL_CLOSURE
         assert msg.type is WSMsgType.ERROR
         assert isinstance(msg.data, ServerTimeoutError)
+        assert str(msg.data) == "No PONG received after 0.05 seconds"
 
 
 async def test_close_websocket_while_ping_inflight(
diff --git a/tests/test_web_websocket_functional.py b/tests/test_web_websocket_functional.py
index b7494d9265f..945096a2af3 100644
--- a/tests/test_web_websocket_functional.py
+++ b/tests/test_web_websocket_functional.py
@@ -797,6 +797,7 @@ async def handler(request: web.Request) -> NoReturn:
     assert ws.close_code == WSCloseCode.ABNORMAL_CLOSURE
     assert ws_server_close_code == WSCloseCode.ABNORMAL_CLOSURE
     assert isinstance(ws_server_exception, asyncio.TimeoutError)
+    assert str(ws_server_exception) == "No PONG received after 0.025 seconds"
     await ws.close()