diff --git a/app/notify_client/notification_api_client.py b/app/notify_client/notification_api_client.py
index 10f0d3e6f..dae4f5825 100644
--- a/app/notify_client/notification_api_client.py
+++ b/app/notify_client/notification_api_client.py
@@ -93,5 +93,10 @@ class NotificationApiClient(NotifyAdminAPIClient):
 
         return self.get(url=get_url)
 
+    def update_notification_to_cancelled(self, service_id, notification_id):
+        return self.post(
+            url='/service/{}/notifications/{}/cancel'.format(service_id, notification_id),
+            data={})
+
 
 notification_api_client = NotificationApiClient()
diff --git a/tests/app/notify_client/test_notification_client.py b/tests/app/notify_client/test_notification_client.py
index aeb051994..6486741e3 100644
--- a/tests/app/notify_client/test_notification_client.py
+++ b/tests/app/notify_client/test_notification_client.py
@@ -85,3 +85,12 @@ def test_get_api_notifications_changes_letter_statuses(mocker):
     assert ret['notifications'][0]['status'] == 'created'
     assert ret['notifications'][1]['status'] == 'created'
     assert ret['notifications'][2]['status'] == 'accepted'
+
+
+def test_update_notification_to_cancelled(mocker):
+    mock_post = mocker.patch('app.notify_client.notification_api_client.NotificationApiClient.post')
+    NotificationApiClient().update_notification_to_cancelled('foo', 'bar')
+    mock_post.assert_called_once_with(
+        url='/service/foo/notifications/bar/cancel',
+        data={},
+    )