diff --git a/CHANGES.rst b/CHANGES.rst
index 64f94e14ec3..9824906c640 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -118,6 +118,9 @@ Bugs fixed
   for objects documented as ``:py:data:`` to be hyperlinked in function signatures.
 * #13858: doctest: doctest blocks are now correctly added to a group defined by the
   configuration variable ``doctest_test_doctest_blocks``.
+* #12797: Fix
+  ``TypeError: Some type variables (...) are not listed in Generic[...]``
+  when inheriting from both Generic and autodoc mocked class.
 
 
 Testing
diff --git a/sphinx/ext/autodoc/mock.py b/sphinx/ext/autodoc/mock.py
index 236174a62f9..3a892fcfebd 100644
--- a/sphinx/ext/autodoc/mock.py
+++ b/sphinx/ext/autodoc/mock.py
@@ -29,6 +29,8 @@ class _MockObject:
     __name__ = ''
     __sphinx_mock__ = True
     __sphinx_decorator_args__: tuple[Any, ...] = ()
+    # Attributes listed here should not be mocked and rather raise an Attribute error:
+    __sphinx_empty_attrs__: set[str] = {'__typing_subst__'}
 
     def __new__(cls, *args: Any, **kwargs: Any) -> Any:  # NoQA: ARG004
         if len(args) == 3 and isinstance(args[1], tuple):
@@ -63,6 +65,8 @@ def __getitem__(self, key: Any) -> _MockObject:
         return _make_subclass(str(key), self.__display_name__, self.__class__)()
 
     def __getattr__(self, key: str) -> _MockObject:
+        if key in self.__sphinx_empty_attrs__:
+            raise AttributeError
         return _make_subclass(key, self.__display_name__, self.__class__)()
 
     def __call__(self, *args: Any, **kwargs: Any) -> Any:
diff --git a/tests/test_extensions/test_ext_autodoc_mock.py b/tests/test_extensions/test_ext_autodoc_mock.py
index b2a0e917bee..0bf6d1ce187 100644
--- a/tests/test_extensions/test_ext_autodoc_mock.py
+++ b/tests/test_extensions/test_ext_autodoc_mock.py
@@ -5,7 +5,7 @@
 import abc
 import sys
 from importlib import import_module
-from typing import TypeVar
+from typing import Generic, TypeVar
 
 import pytest
 
@@ -57,6 +57,28 @@ class SubClass2(mock.SomeClass[T]):
     assert SubClass2.__doc__ == 'docstring of SubClass'
     assert isinstance(obj2, SubClass2)
 
+    # test subclass with typing.Generic
+    # Creating this class would raise an error on Python3.11+
+    # as mock objects are detected as typevars if hasattr(__typing_subst__) is True.
+
+    assert not hasattr(mock.SomeClass, '__typing_subst__')
+    S = TypeVar('S')
+
+    class GenericClass(mock.SomeClass, Generic[T, S]):
+        """docstring of GenericSubclass"""
+
+    obj3 = GenericClass()
+    assert isinstance(obj3, _MockObject)
+    assert isinstance(obj3.some_attr, _MockObject)
+    assert isinstance(obj3.some_method(), _MockObject)
+    assert isinstance(obj3.attr1.attr2, _MockObject)
+    assert isinstance(obj3.attr1.attr2.meth(), _MockObject)
+
+    # check that Generic Subscriptions still works
+
+    class GenericSubclass(GenericClass[mock.MockedClass, S]):
+        """docstring of GenericSubclass"""
+
 
 def test_mock() -> None:
     modname = 'sphinx.unknown'