diff --git a/changelog/6802.bugfix.rst b/changelog/6802.bugfix.rst
new file mode 100644
index 00000000000..af9ebef3a39
--- /dev/null
+++ b/changelog/6802.bugfix.rst
@@ -0,0 +1 @@
+The :fixture:`testdir fixture <testdir>` works within doctests now.
diff --git a/src/_pytest/nodes.py b/src/_pytest/nodes.py
index c452e63c48e..d9a607db8d3 100644
--- a/src/_pytest/nodes.py
+++ b/src/_pytest/nodes.py
@@ -548,7 +548,16 @@ class Item(Node):
 
     nextitem = None
 
-    def __init__(self, name, parent=None, config=None, session=None, nodeid=None):
+    def __init__(
+        self,
+        name,
+        parent=None,
+        config=None,
+        session=None,
+        nodeid=None,
+        *,
+        originalname: str = None
+    ):
         super().__init__(name, parent, config, session, nodeid=nodeid)
         self._report_sections = []  # type: List[Tuple[str, str, str]]
 
@@ -556,6 +565,12 @@ def __init__(self, name, parent=None, config=None, session=None, nodeid=None):
         #: defined properties for this test.
         self.user_properties = []  # type: List[Tuple[str, Any]]
 
+        #: Original function name, without any decorations (for example
+        #: parametrization adds a ``"[...]"`` suffix to function names).
+        #:
+        #: .. versionadded:: 3.0
+        self.originalname = originalname
+
     def runtest(self) -> None:
         raise NotImplementedError("runtest must be implemented by Item subclass")
 
diff --git a/src/_pytest/pytester/__init__.py b/src/_pytest/pytester/__init__.py
index 5097665bc1a..11f6007123e 100644
--- a/src/_pytest/pytester/__init__.py
+++ b/src/_pytest/pytester/__init__.py
@@ -599,7 +599,7 @@ def __init__(self, request: FixtureRequest, tmpdir_factory: TempdirFactory) -> N
         self._mod_collections = (
             WeakKeyDictionary()
         )  # type: WeakKeyDictionary[Module, List[Union[Item, Collector]]]
-        name = request.function.__name__
+        name = self._name = request.node.originalname or request.node.name
         self.tmpdir = tmpdir_factory.mktemp(name, numbered=True)  # type: py.path.local
         """The base temporary directory.
 
@@ -675,9 +675,8 @@ def to_text(s):
             return s.decode(encoding) if isinstance(s, bytes) else str(s)
 
         if lines:
-            funcname = self.request.function.__name__  # type: str
             lines = "\n".join(to_text(x) for x in lines)
-            items.insert(0, (funcname, lines))
+            items.insert(0, (self._name, lines))
 
         if not items:
             raise ValueError("no files to create")
@@ -872,7 +871,7 @@ def copy_example(self, name=None):
             example_dir = example_dir.join(*extra_element.args)
 
         if name is None:
-            func_name = self.request.function.__name__
+            func_name = self._name
             maybe_dir = example_dir / func_name
             maybe_file = example_dir / (func_name + ".py")
 
@@ -1256,7 +1255,7 @@ def getmodulecol(self, source, configargs=(), withinit=False):
             path = self.tmpdir.join(str(source))
             assert not withinit, "not supported for paths"
         else:
-            kw = {self.request.function.__name__: Source(source).strip()}
+            kw = {self._name: Source(source).strip()}
             path = self.makepyfile(**kw)
         if withinit:
             self.makepyfile(__init__="#")
diff --git a/src/_pytest/python.py b/src/_pytest/python.py
index 4989d6b3984..2f0832de8e5 100644
--- a/src/_pytest/python.py
+++ b/src/_pytest/python.py
@@ -1411,7 +1411,9 @@ def __init__(
         fixtureinfo: Optional[FuncFixtureInfo] = None,
         originalname=None,
     ) -> None:
-        super().__init__(name, parent, config=config, session=session)
+        super().__init__(
+            name, parent, config=config, session=session, originalname=originalname
+        )
         self._args = args
         if callobj is not NOTSET:
             self.obj = callobj
@@ -1450,12 +1452,6 @@ def __init__(
         self.fixturenames = fixtureinfo.names_closure
         self._initrequest()
 
-        #: original function name, without any decorations (for example
-        #: parametrization adds a ``"[...]"`` suffix to function names).
-        #:
-        #: .. versionadded:: 3.0
-        self.originalname = originalname
-
     @classmethod
     def from_parent(cls, parent, **kw):  # todo: determine sound type limitations
         """
diff --git a/testing/test_pytester.py b/testing/test_pytester.py
index 1cef02cdde0..8b687999f29 100644
--- a/testing/test_pytester.py
+++ b/testing/test_pytester.py
@@ -92,6 +92,29 @@ def test_hello(testdir):
     result.assert_outcomes(passed=1)
 
 
+def test_testdir_with_doctest(testdir: "Testdir") -> None:
+    """Check that testdir can be used within doctests.
+
+    It used to use `request.function`, which is `None` with doctests."""
+    testdir.makepyfile(
+        **{
+            "sub/t-doctest.py": """
+        '''
+        >>> import os
+        >>> testdir = getfixture("testdir")
+        >>> str(testdir.makepyfile("content")).replace(os.sep, '/')
+        '.../basetemp/sub.t-doctest0/sub.py'
+        '''
+    """,
+            "sub/__init__.py": "",
+        }
+    )
+    result = testdir.runpytest(
+        "-p", "pytester", "--doctest-modules", "sub/t-doctest.py"
+    )
+    assert result.ret == 0
+
+
 def test_runresult_assertion_on_xfail(testdir) -> None:
     testdir.makepyfile(
         """