diff --git a/docs/source/user-guide/operators.md b/docs/source/user-guide/operators.md
index 32b4b8a80..e3a3ac522 100644
--- a/docs/source/user-guide/operators.md
+++ b/docs/source/user-guide/operators.md
@@ -35,3 +35,4 @@ not supported by Comet will fall back to regular Spark execution.
 | BroadcastHashJoinExec                        |       |
 | Shuffle                                      |       |
 | Expand                                       |       |
+| Union                                        |       |