diff --git a/google/cloud/storage/client.py b/google/cloud/storage/client.py
index 2f56d8719..74b6061c0 100644
--- a/google/cloud/storage/client.py
+++ b/google/cloud/storage/client.py
@@ -297,6 +297,18 @@ def universe_domain(self):
     def api_endpoint(self):
         return self._connection.API_BASE_URL
 
+    def update_user_agent(self, user_agent):
+        """Update the user-agent string for this client.
+
+        :type user_agent: str
+        :param user_agent: The string to add to the user-agent.
+        """
+        existing_user_agent = self._connection._client_info.user_agent
+        if existing_user_agent is None:
+            self._connection.user_agent = user_agent
+        else:
+            self._connection.user_agent = f"{user_agent} {existing_user_agent}"
+
     @property
     def _connection(self):
         """Get connection or batch on the client.
diff --git a/tests/unit/test_client.py b/tests/unit/test_client.py
index 99de31961..d5723740e 100644
--- a/tests/unit/test_client.py
+++ b/tests/unit/test_client.py
@@ -1528,6 +1528,34 @@ def test_create_bucket_w_conflict_w_user_project(self):
             _target_object=mock.ANY,
         )
 
+    def test_update_user_agent_when_default_clientinfo_provided(self):
+        from google.cloud._http import ClientInfo
+
+        client_info = ClientInfo()
+
+        client = self._make_one(project=None, client_info=client_info)
+        self.assertGreater(len(client._connection.user_agent), 0)
+
+        client.update_user_agent("my-test-agent/1.0")
+        self.assertIn("my-test-agent/1.0", client._connection.user_agent)
+
+    def test_update_user_agent_when_none_clientinfo_provided(self):
+        client = self._make_one(project=None)
+        client.update_user_agent("my-test-agent/1.0")
+
+        self.assertIn("my-test-agent/1.0", client._connection.user_agent)
+
+    def test_update_user_agent_with_existing_user_agent(self):
+        from google.cloud._http import ClientInfo
+
+        client_info = ClientInfo(user_agent="existing-agent/2.0")
+        client = self._make_one(project=None, client_info=client_info)
+        client.update_user_agent("my-test-agent/1.0")
+
+        self.assertIn(
+            "my-test-agent/1.0 existing-agent/2.0", client._connection.user_agent
+        )
+
     @mock.patch("warnings.warn")
     def test_create_bucket_w_requester_pays_deprecated(self, mock_warn):
         from google.cloud.storage.bucket import Bucket