diff --git a/firebase_admin/_user_mgt.py b/firebase_admin/_user_mgt.py
index aa0dfb0a..22802979 100644
--- a/firebase_admin/_user_mgt.py
+++ b/firebase_admin/_user_mgt.py
@@ -25,7 +25,7 @@
 from firebase_admin import _rfc3339
 from firebase_admin import _user_identifier
 from firebase_admin import _user_import
-from firebase_admin._user_import import ErrorInfo
+from firebase_admin._user_import import ErrorInfo, UserProvider
 
 
 MAX_LIST_USERS_RESULTS = 1000
@@ -688,7 +688,8 @@ def create_user(self, uid=None, display_name=None, email=None, phone_number=None
 
     def update_user(self, uid, display_name=None, email=None, phone_number=None,
                     photo_url=None, password=None, disabled=None, email_verified=None,
-                    valid_since=None, custom_claims=None, providers_to_delete=None):
+                    valid_since=None, custom_claims=None, providers_to_delete=None,
+                    provider_to_add: UserProvider | None=None):
         """Updates an existing user account with the specified properties"""
         payload = {
             'localId': _auth_utils.validate_uid(uid, required=True),
@@ -727,6 +728,9 @@ def update_user(self, uid, display_name=None, email=None, phone_number=None,
                 custom_claims, dict) else custom_claims
             payload['customAttributes'] = _auth_utils.validate_custom_claims(json_claims)
 
+        if provider_to_add:
+            payload['linkProviderUserInfo'] = provider_to_add.to_dict()
+
         if remove_provider:
             payload['deleteProvider'] = list(set(remove_provider))
 
diff --git a/integration/test_auth.py b/integration/test_auth.py
index e1d01a25..dfcab5f8 100644
--- a/integration/test_auth.py
+++ b/integration/test_auth.py
@@ -16,6 +16,7 @@
 import base64
 import datetime
 import random
+import re
 import string
 import time
 from typing import List
@@ -30,6 +31,7 @@
 import firebase_admin
 from firebase_admin import auth
 from firebase_admin import credentials
+from firebase_admin import exceptions
 
 
 _verify_token_url = 'https://www.googleapis.com/identitytoolkit/v3/relyingparty/verifyCustomToken'
@@ -496,6 +498,32 @@ def test_disable_user(new_user_with_params):
     assert user.disabled is True
     assert len(user.provider_data) == 1
 
+def test_add_valid_provider(new_user_with_provider):
+    new_provider = auth.UserProvider(uid=new_user_with_provider.uid, provider_id='microsoft.com')
+    existing_provider_ids = [provider.provider_id for provider in new_user_with_provider.provider_data]
+    assert new_provider.provider_id not in existing_provider_ids
+    user = auth.update_user(new_user_with_provider.uid, provider_to_add=new_provider)
+    assert user.uid == new_user_with_provider.uid
+    new_provider_ids = [provider.provider_id for provider in user.provider_data]
+    assert sorted(new_provider_ids) == sorted(existing_provider_ids + [new_provider.provider_id])
+
+def test_add_invalid_provider(new_user_with_provider):
+    new_provider = auth.UserProvider(uid=new_user_with_provider.uid, provider_id='xyz.com')
+    existing_provider_ids = [provider.provider_id for provider in new_user_with_provider.provider_data]
+    assert new_provider.provider_id not in existing_provider_ids
+    with pytest.raises(exceptions.InvalidArgumentError, match=re.escape(
+        f"Error while calling Auth service (INVALID_PROVIDER_ID ). provider {new_provider.provider_id} is not supported for linking."
+    )):
+        auth.update_user(new_user_with_provider.uid, provider_to_add=new_provider)
+
+def test_add_duplicate_provider(new_user_with_provider):
+    google_uid, google_email = _random_id()
+    duplicate_provider = auth.UserProvider(uid=google_uid, provider_id='google.com', email=google_email)
+    with pytest.raises(exceptions.InvalidArgumentError, match=re.escape(
+        f"Error while calling Auth service (PROVIDER_ALREADY_LINKED)."
+    )):
+        auth.update_user(new_user_with_provider.uid, provider_to_add=duplicate_provider)
+
 def test_remove_provider(new_user_with_provider):
     provider_ids = [provider.provider_id for provider in new_user_with_provider.provider_data]
     assert 'google.com' in provider_ids