diff --git a/CHANGES b/CHANGES
index 9db991af8..52f2abdfe 100644
--- a/CHANGES
+++ b/CHANGES
@@ -85,6 +85,7 @@ Bugs fixed
 * #6857: autodoc: failed to detect a classmethod on Enum class
 * #7562: autodoc: a typehint contains spaces is wrongly rendered under
   autodoc_typehints='description' mode
+* #7551: autodoc: failed to import nested class
 * #7551: autosummary: a nested class is indexed as non-nested class
 * #7535: sphinx-autogen: crashes when custom template uses inheritance
 * #7536: sphinx-autogen: crashes when template uses i18n feature
diff --git a/sphinx/ext/autodoc/__init__.py b/sphinx/ext/autodoc/__init__.py
index 7cf8b584b..8bf2e82a2 100644
--- a/sphinx/ext/autodoc/__init__.py
+++ b/sphinx/ext/autodoc/__init__.py
@@ -31,7 +31,7 @@ from sphinx.locale import _, __
 from sphinx.pycode import ModuleAnalyzer, PycodeError
 from sphinx.util import inspect
 from sphinx.util import logging
-from sphinx.util import rpartition
+from sphinx.util import split_full_qualified_name
 from sphinx.util.docstrings import extract_metadata, prepare_docstring
 from sphinx.util.inspect import getdoc, object_description, safe_getattr, stringify_signature
 from sphinx.util.typing import stringify as stringify_typehint
@@ -312,7 +312,8 @@ class Documenter:
             modname = None
             parents = []
 
-        self.modname, self.objpath = self.resolve_name(modname, parents, path, base)
+        with mock(self.env.config.autodoc_mock_imports):
+            self.modname, self.objpath = self.resolve_name(modname, parents, path, base)
 
         if not self.modname:
             return False
@@ -898,8 +899,14 @@ class ModuleLevelDocumenter(Documenter):
                      ) -> Tuple[str, List[str]]:
         if modname is None:
             if path:
-                modname = path.rstrip('.')
-            else:
+                stripped = path.rstrip('.')
+                modname, qualname = split_full_qualified_name(stripped)
+                if qualname:
+                    parents = qualname.split(".")
+                else:
+                    parents = []
+
+            if modname is None:
                 # if documenting a toplevel object without explicit module,
                 # it can be contained in another auto directive ...
                 modname = self.env.temp_data.get('autodoc:module')
@@ -932,8 +939,13 @@ class ClassLevelDocumenter(Documenter):
                 # ... if still None, there's no way to know
                 if mod_cls is None:
                     return None, []
-            modname, cls = rpartition(mod_cls, '.')
-            parents = [cls]
+
+            try:
+                modname, qualname = split_full_qualified_name(mod_cls)
+                parents = qualname.split(".")
+            except ImportError:
+                parents = mod_cls.split(".")
+
             # if the module name is still missing, get it like above
             if not modname:
                 modname = self.env.temp_data.get('autodoc:module')
diff --git a/tests/test_ext_autodoc.py b/tests/test_ext_autodoc.py
index 23ba2e733..4833daa8b 100644
--- a/tests/test_ext_autodoc.py
+++ b/tests/test_ext_autodoc.py
@@ -103,27 +103,27 @@ def test_parse_name(app):
     directive = make_directive_bridge(app.env)
 
     # for modules
-    verify('module', 'test_autodoc', ('test_autodoc', [], None, None))
-    verify('module', 'test.test_autodoc', ('test.test_autodoc', [], None, None))
+    verify('module', 'test_ext_autodoc', ('test_ext_autodoc', [], None, None))
+    verify('module', 'test.test_ext_autodoc', ('test.test_ext_autodoc', [], None, None))
     verify('module', 'test(arg)', ('test', [], 'arg', None))
     assert 'signature arguments' in app._warning.getvalue()
 
     # for functions/classes
-    verify('function', 'test_autodoc.raises',
-           ('test_autodoc', ['raises'], None, None))
-    verify('function', 'test_autodoc.raises(exc) -> None',
-           ('test_autodoc', ['raises'], 'exc', 'None'))
-    directive.env.temp_data['autodoc:module'] = 'test_autodoc'
-    verify('function', 'raises', ('test_autodoc', ['raises'], None, None))
+    verify('function', 'test_ext_autodoc.raises',
+           ('test_ext_autodoc', ['raises'], None, None))
+    verify('function', 'test_ext_autodoc.raises(exc) -> None',
+           ('test_ext_autodoc', ['raises'], 'exc', 'None'))
+    directive.env.temp_data['autodoc:module'] = 'test_ext_autodoc'
+    verify('function', 'raises', ('test_ext_autodoc', ['raises'], None, None))
     del directive.env.temp_data['autodoc:module']
-    directive.env.ref_context['py:module'] = 'test_autodoc'
-    verify('function', 'raises', ('test_autodoc', ['raises'], None, None))
-    verify('class', 'Base', ('test_autodoc', ['Base'], None, None))
+    directive.env.ref_context['py:module'] = 'test_ext_autodoc'
+    verify('function', 'raises', ('test_ext_autodoc', ['raises'], None, None))
+    verify('class', 'Base', ('test_ext_autodoc', ['Base'], None, None))
 
     # for members
     directive.env.ref_context['py:module'] = 'foo'
     verify('method', 'util.SphinxTestApp.cleanup',
-           ('util', ['SphinxTestApp', 'cleanup'], None, None))
+           ('foo', ['util', 'SphinxTestApp', 'cleanup'], None, None))
     directive.env.ref_context['py:module'] = 'util'
     directive.env.ref_context['py:class'] = 'Foo'
     directive.env.temp_data['autodoc:class'] = 'SphinxTestApp'
@@ -735,14 +735,14 @@ def test_autodoc_inner_class(app):
     actual = do_autodoc(app, 'class', 'target.Outer.Inner', options)
     assert list(actual) == [
         '',
-        '.. py:class:: Inner',
-        '   :module: target.Outer',
+        '.. py:class:: Outer.Inner',
+        '   :module: target',
         '',
         '   Foo',
         '',
         '',
-        '   .. py:method:: Inner.meth()',
-        '      :module: target.Outer',
+        '   .. py:method:: Outer.Inner.meth()',
+        '      :module: target',
         '',
         '      Foo',
         '',