diff --git a/Lib/test/test_warnings.py b/Lib/test/test_warnings.py
index eec2c242183..43b3b9c1287 100644
--- a/Lib/test/test_warnings.py
+++ b/Lib/test/test_warnings.py
@@ -61,6 +61,25 @@ class BaseTest:
         sys.modules['warnings'] = original_warnings
         super(BaseTest, self).tearDown()
 
+class PublicAPITests(BaseTest):
+
+    """Ensures that the correct values are exposed in the
+    public API.
+    """
+
+    def test_module_all_attribute(self):
+        self.assertTrue(hasattr(self.module, '__all__'))
+        target_api = ["warn", "warn_explicit", "showwarning",
+                      "formatwarning", "filterwarnings", "simplefilter",
+                      "resetwarnings", "catch_warnings"]
+        self.assertSetEqual(set(self.module.__all__),
+                            set(target_api))
+
+class CPublicAPITests(PublicAPITests, unittest.TestCase):
+    module = c_warnings
+
+class PyPublicAPITests(PublicAPITests, unittest.TestCase):
+    module = py_warnings
 
 class FilterTests(BaseTest):
 
diff --git a/Lib/warnings.py b/Lib/warnings.py
index a427e3510ec..eeeba653741 100644
--- a/Lib/warnings.py
+++ b/Lib/warnings.py
@@ -2,7 +2,8 @@
 
 import sys
 
-__all__ = ["warn", "showwarning", "formatwarning", "filterwarnings",
+__all__ = ["warn", "warn_explicit", "showwarning",
+           "formatwarning", "filterwarnings", "simplefilter",
            "resetwarnings", "catch_warnings"]
 
 
diff --git a/Misc/ACKS b/Misc/ACKS
index b16dd70feb1..4986dc619d5 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -1054,6 +1054,7 @@ Antoine Pitrou
 Jean-François Piéronne
 Oleg Plakhotnyuk
 Remi Pointel
+Jon Poler
 Ariel Poliak
 Guilherme Polo
 Illia Polosukhin
diff --git a/Misc/NEWS b/Misc/NEWS
index 9c4f5606a3d..9396ac906f4 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -27,6 +27,8 @@ Core and Builtins
 Library
 -------
 
+-- Issue #22191: Fix warnings.__all__.
+
 - Issue #15696: Add a __sizeof__ implementation for mmap objects on Windows.
 
 - Issue #22068: Avoided reference loops with Variables and Fonts in Tkinter.