diff --git a/CHANGES/5853.bugfix b/CHANGES/5853.bugfix
new file mode 100644
index 00000000000..3b3b03a374f
--- /dev/null
+++ b/CHANGES/5853.bugfix
@@ -0,0 +1 @@
+Don't cancel current task when entering a cancelled timer.
diff --git a/aiohttp/helpers.py b/aiohttp/helpers.py
index 948b12f99d8..c60397931fb 100644
--- a/aiohttp/helpers.py
+++ b/aiohttp/helpers.py
@@ -675,7 +675,6 @@ def __enter__(self) -> BaseTimerContext:
             )
 
         if self._cancelled:
-            task.cancel()
             raise asyncio.TimeoutError from None
 
         self._tasks.append(task)
diff --git a/tests/test_helpers.py b/tests/test_helpers.py
index 8f029f15666..564ed783848 100644
--- a/tests/test_helpers.py
+++ b/tests/test_helpers.py
@@ -362,7 +362,7 @@ def test_timeout_handle_cb_exc(loop) -> None:
     assert not handle._callbacks
 
 
-def test_timer_context_cancelled() -> None:
+def test_timer_context_not_cancelled() -> None:
     with mock.patch("aiohttp.helpers.asyncio") as m_asyncio:
         m_asyncio.TimeoutError = asyncio.TimeoutError
         loop = mock.Mock()
@@ -373,7 +373,7 @@ def test_timer_context_cancelled() -> None:
             with ctx:
                 pass
 
-        assert m_asyncio.current_task.return_value.cancel.called
+        assert not m_asyncio.current_task.return_value.cancel.called
 
 
 def test_timer_context_no_task(loop) -> None: