diff --git a/CHANGES b/CHANGES
index c79f7c6fe..d4df88f30 100644
--- a/CHANGES
+++ b/CHANGES
@@ -132,6 +132,7 @@ Bugs fixed
 * #7267: autodoc: error message for invalid directive options has wrong location
 * #7329: autodoc: info-field-list is wrongly generated from type hints into the
   class description even if ``autoclass_content='class'`` set
+* #7331: autodoc: a cython-function is not recognized as a function
 * #5637: inheritance_diagram: Incorrect handling of nested class names
 * #7139: ``code-block:: guess`` does not work
 * #7325: html: source_suffix containing dot leads to wrong source link
diff --git a/setup.py b/setup.py
index 088d5b8e7..a427d5493 100644
--- a/setup.py
+++ b/setup.py
@@ -52,6 +52,7 @@ extras_require = {
         'pytest-cov',
         'html5lib',
         'typed_ast',  # for py35-37
+        'cython',
     ],
 }
 
diff --git a/sphinx/ext/autodoc/__init__.py b/sphinx/ext/autodoc/__init__.py
index a81842c4a..7b6b3e4aa 100644
--- a/sphinx/ext/autodoc/__init__.py
+++ b/sphinx/ext/autodoc/__init__.py
@@ -1011,7 +1011,8 @@ class FunctionDocumenter(DocstringSignatureMixin, ModuleLevelDocumenter):  # typ
         if self.env.config.autodoc_typehints in ('none', 'description'):
             kwargs.setdefault('show_annotation', False)
 
-        if inspect.isbuiltin(self.object) or inspect.ismethoddescriptor(self.object):
+        if ((inspect.isbuiltin(self.object) or inspect.ismethoddescriptor(self.object)) and
+                not inspect.is_cython_function_or_method(self.object)):
             # cannot introspect arguments of a C function or method
             return None
         try:
@@ -1430,7 +1431,8 @@ class MethodDocumenter(DocstringSignatureMixin, ClassLevelDocumenter):  # type:
         if self.env.config.autodoc_typehints == 'none':
             kwargs.setdefault('show_annotation', False)
 
-        if inspect.isbuiltin(self.object) or inspect.ismethoddescriptor(self.object):
+        if ((inspect.isbuiltin(self.object) or inspect.ismethoddescriptor(self.object)) and
+                not inspect.is_cython_function_or_method(self.object)):
             # can never get arguments of a C function or method
             return None
         if inspect.isstaticmethod(self.object, cls=self.parent, name=self.object_name):
diff --git a/sphinx/util/inspect.py b/sphinx/util/inspect.py
index d22df7656..855b11d83 100644
--- a/sphinx/util/inspect.py
+++ b/sphinx/util/inspect.py
@@ -197,6 +197,14 @@ def isabstractmethod(obj: Any) -> bool:
     return safe_getattr(obj, '__isabstractmethod__', False) is True
 
 
+def is_cython_function_or_method(obj: Any) -> bool:
+    """Check if the object is a function or method in cython."""
+    try:
+        return obj.__class__.__name__ == 'cython_function_or_method'
+    except AttributeError:
+        return False
+
+
 def isattributedescriptor(obj: Any) -> bool:
     """Check if the object is an attribute like descriptor."""
     if inspect.isdatadescriptor(object):
@@ -207,6 +215,9 @@ def isattributedescriptor(obj: Any) -> bool:
         if isfunction(obj) or isbuiltin(obj) or inspect.ismethod(obj):
             # attribute must not be either function, builtin and method
             return False
+        elif is_cython_function_or_method(obj):
+            # attribute must not be either function and method (for cython)
+            return False
         elif inspect.isclass(obj):
             # attribute must not be a class
             return False
diff --git a/tests/roots/test-ext-autodoc/target/cython.pyx b/tests/roots/test-ext-autodoc/target/cython.pyx
new file mode 100644
index 000000000..1457db3c9
--- /dev/null
+++ b/tests/roots/test-ext-autodoc/target/cython.pyx
@@ -0,0 +1,12 @@
+# cython: binding=True
+
+def foo(*args, **kwargs):
+    """Docstring."""
+
+
+class Class:
+    """Docstring."""
+
+    def meth(self, name: str, age: int = 0) -> None:
+        """Docstring."""
+        pass
diff --git a/tests/test_autodoc.py b/tests/test_autodoc.py
index 012292999..741c4bb60 100644
--- a/tests/test_autodoc.py
+++ b/tests/test_autodoc.py
@@ -22,6 +22,13 @@ from sphinx.testing.util import SphinxTestApp, Struct  # NOQA
 from sphinx.util import logging
 from sphinx.util.docutils import LoggingReporter
 
+try:
+    # Enable pyximport to test cython module
+    import pyximport
+    pyximport.install()
+except ImportError:
+    pyximport = None
+
 app = None
 
 
@@ -1609,3 +1616,34 @@ def test_singledispatchmethod():
         '      A method for general use.',
         '',
     ]
+
+
+@pytest.mark.usefixtures('setup_test')
+@pytest.mark.skipif(pyximport is None, reason='cython is not installed')
+def test_cython():
+    options = {"members": None,
+               "undoc-members": None}
+    actual = do_autodoc(app, 'module', 'target.cython', options)
+    assert list(actual) == [
+        '',
+        '.. py:module:: target.cython',
+        '',
+        '',
+        '.. py:class:: Class',
+        '   :module: target.cython',
+        '',
+        '   Docstring.',
+        '',
+        '',
+        '   .. py:method:: Class.meth(name: str, age: int = 0) -> None',
+        '      :module: target.cython',
+        '',
+        '      Docstring.',
+        '',
+        '',
+        '.. py:function:: foo(*args, **kwargs)',
+        '   :module: target.cython',
+        '',
+        '   Docstring.',
+        '',
+    ]