diff --git a/CHANGES/9870.misc.rst b/CHANGES/9870.misc.rst
new file mode 100644
index 00000000000..caa8f45e522
--- /dev/null
+++ b/CHANGES/9870.misc.rst
@@ -0,0 +1 @@
+Added support for the ``partitioned`` attribute in the ``set_cookie`` method.
diff --git a/aiohttp/helpers.py b/aiohttp/helpers.py
index f04b74833bc..7f6506939f4 100644
--- a/aiohttp/helpers.py
+++ b/aiohttp/helpers.py
@@ -940,6 +940,7 @@ def set_cookie(
         secure: Optional[bool] = None,
         httponly: Optional[bool] = None,
         samesite: Optional[str] = None,
+        partitioned: Optional[bool] = None,
     ) -> None:
         """Set or update response cookie.
 
@@ -974,6 +975,9 @@ def set_cookie(
         if samesite is not None:
             c["samesite"] = samesite
 
+        if partitioned is not None:
+            c["partitioned"] = partitioned
+
         if DEBUG:
             cookie_length = len(c.output(header="")[1:])
             if cookie_length > COOKIE_MAX_LENGTH:
diff --git a/docs/web_reference.rst b/docs/web_reference.rst
index f9d1d5e839e..7f661f44f71 100644
--- a/docs/web_reference.rst
+++ b/docs/web_reference.rst
@@ -705,7 +705,8 @@ and :ref:`aiohttp-web-signals` handlers::
 
    .. method:: set_cookie(name, value, *, path='/', expires=None, \
                           domain=None, max_age=None, \
-                          secure=None, httponly=None, samesite=None)
+                          secure=None, httponly=None, samesite=None, \
+                          partitioned=None)
 
       Convenient way for setting :attr:`cookies`, allows to specify
       some additional properties like *max_age* in a single call.
@@ -753,6 +754,11 @@ and :ref:`aiohttp-web-signals` handlers::
 
             .. versionadded:: 3.7
 
+      :param bool partitioned: ``True`` to set a partitioned cookie.
+         Available in Python 3.14+. (optional)
+
+            .. versionadded:: 3.12
+
    .. method:: del_cookie(name, *, path='/', domain=None)
 
       Deletes cookie.
diff --git a/tests/test_helpers.py b/tests/test_helpers.py
index 69f57957c88..80d3a0e355e 100644
--- a/tests/test_helpers.py
+++ b/tests/test_helpers.py
@@ -976,6 +976,19 @@ def test_cookies_mixin_path() -> None:
     )
 
 
+@pytest.mark.skipif(sys.version_info < (3, 14), reason="No partitioned support")
+def test_cookies_mixin_partitioned() -> None:
+    sut = CookieImplementation()
+
+    assert sut.cookies == {}
+
+    sut.set_cookie("name", "value", partitioned=False)
+    assert str(sut.cookies) == "Set-Cookie: name=value; Path=/"
+
+    sut.set_cookie("name", "value", partitioned=True)
+    assert str(sut.cookies) == "Set-Cookie: name=value; Partitioned; Path=/"
+
+
 def test_sutonse_cookie__issue_del_cookie() -> None:
     sut = CookieImplementation()