diff --git a/telethon/client/chats.py b/telethon/client/chats.py
index ef7a10cb..dfbeddcc 100644
--- a/telethon/client/chats.py
+++ b/telethon/client/chats.py
@@ -22,6 +22,7 @@ class _ChatAction:
         'contact': types.SendMessageChooseContactAction(),
         'game': types.SendMessageGamePlayAction(),
         'location': types.SendMessageGeoLocationAction(),
+        'sticker': types.SendMessageChooseStickerAction(),
 
         'record-audio': types.SendMessageRecordAudioAction(),
         'record-voice': types.SendMessageRecordAudioAction(),  # alias
@@ -773,6 +774,7 @@ class ChatMethods:
                 * ``'contact'``: choosing a contact.
                 * ``'game'``: playing a game.
                 * ``'location'``: choosing a geo location.
+                * ``'sticker'``: choosing a sticker.
                 * ``'record-audio'``: recording a voice note.
                   You may use ``'record-voice'`` as alias.
                 * ``'record-round'``: recording a round video.
diff --git a/telethon/events/userupdate.py b/telethon/events/userupdate.py
index c0a07619..e0179f01 100644
--- a/telethon/events/userupdate.py
+++ b/telethon/events/userupdate.py
@@ -136,6 +136,7 @@ class UserUpdate(EventBuilder):
             """
             return isinstance(self.action, (
                 types.SendMessageChooseContactAction,
+                types.SendMessageChooseStickerAction,
                 types.SendMessageUploadAudioAction,
                 types.SendMessageUploadDocumentAction,
                 types.SendMessageUploadPhotoAction,
@@ -228,6 +229,14 @@ class UserUpdate(EventBuilder):
             """
             return isinstance(self.action, types.SendMessageUploadDocumentAction)
 
+        @property
+        @_requires_action
+        def sticker(self):
+            """
+            `True` if what's being uploaded is a sticker.
+            """
+            return isinstance(self.action, types.SendMessageChooseStickerAction)
+
         @property
         @_requires_action
         def photo(self):