diff --git a/Lib/mimetypes.py b/Lib/mimetypes.py
index 1aa32467e278a3..f6c43b3b92bc50 100644
--- a/Lib/mimetypes.py
+++ b/Lib/mimetypes.py
@@ -517,6 +517,7 @@ def _default_mime_types():
         '.aiff'   : 'audio/x-aiff',
         '.ra'     : 'audio/x-pn-realaudio',
         '.wav'    : 'audio/x-wav',
+        '.avif'   : 'image/avif',
         '.bmp'    : 'image/bmp',
         '.gif'    : 'image/gif',
         '.ief'    : 'image/ief',
@@ -589,6 +590,7 @@ def _default_mime_types():
         '.pict': 'image/pict',
         '.pct' : 'image/pict',
         '.pic' : 'image/pict',
+        '.webp': 'image/webp',
         '.xul' : 'text/xul',
         }
 
diff --git a/Lib/test/test_mimetypes.py b/Lib/test/test_mimetypes.py
index f2b103693a9b2c..d64aee71fc48b1 100644
--- a/Lib/test/test_mimetypes.py
+++ b/Lib/test/test_mimetypes.py
@@ -96,12 +96,14 @@ def test_non_standard_types(self):
         # First try strict
         eq(self.db.guess_type('foo.xul', strict=True), (None, None))
         eq(self.db.guess_extension('image/jpg', strict=True), None)
+        eq(self.db.guess_extension('image/webp', strict=True), None)
         # And then non-strict
         eq(self.db.guess_type('foo.xul', strict=False), ('text/xul', None))
         eq(self.db.guess_type('foo.XUL', strict=False), ('text/xul', None))
         eq(self.db.guess_type('foo.invalid', strict=False), (None, None))
         eq(self.db.guess_extension('image/jpg', strict=False), '.jpg')
         eq(self.db.guess_extension('image/JPG', strict=False), '.jpg')
+        eq(self.db.guess_extension('image/webp', strict=False), '.webp')
 
     def test_filename_with_url_delimiters(self):
         # bpo-38449: URL delimiters cases should be handled also.
@@ -180,6 +182,7 @@ def check_extensions():
             self.assertEqual(mimetypes.guess_extension('application/x-troff'), '.roff')
             self.assertEqual(mimetypes.guess_extension('application/xml'), '.xsl')
             self.assertEqual(mimetypes.guess_extension('audio/mpeg'), '.mp3')
+            self.assertEqual(mimetypes.guess_extension('image/avif'), '.avif')
             self.assertEqual(mimetypes.guess_extension('image/jpeg'), '.jpg')
             self.assertEqual(mimetypes.guess_extension('image/tiff'), '.tiff')
             self.assertEqual(mimetypes.guess_extension('message/rfc822'), '.eml')
diff --git a/Misc/NEWS.d/next/Library/2022-02-02-04-51-39.bpo-45639.N8XrGO.rst b/Misc/NEWS.d/next/Library/2022-02-02-04-51-39.bpo-45639.N8XrGO.rst
new file mode 100644
index 00000000000000..332008bf9c4723
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2022-02-02-04-51-39.bpo-45639.N8XrGO.rst
@@ -0,0 +1 @@
+``image/avif`` and ``image/webp`` were added to :mod:`mimetypes`.