diff --git a/backends-velox/src/test/scala/org/apache/gluten/execution/ScalarFunctionsValidateSuite.scala b/backends-velox/src/test/scala/org/apache/gluten/execution/ScalarFunctionsValidateSuite.scala
index 9d0a926e3b0f..cd9819c3e8e7 100644
--- a/backends-velox/src/test/scala/org/apache/gluten/execution/ScalarFunctionsValidateSuite.scala
+++ b/backends-velox/src/test/scala/org/apache/gluten/execution/ScalarFunctionsValidateSuite.scala
@@ -661,6 +661,15 @@ class ScalarFunctionsValidateSuite extends FunctionsValidateTest {
                          | from lineitem limit 100""".stripMargin) {
       checkGlutenOperatorMatch[ProjectExecTransformer]
     }
+
+    runQueryAndCompare("""SELECT input_file_name(), l_orderkey
+                         | from
+                         | (select l_orderkey from lineitem
+                         | union all
+                         | select o_orderkey as l_orderkey from orders)
+                         | limit 100""".stripMargin) {
+      checkGlutenOperatorMatch[ProjectExecTransformer]
+    }
   }
 
   test("Test spark_partition_id function") {
diff --git a/gluten-core/src/main/scala/org/apache/gluten/extension/columnar/OffloadSingleNode.scala b/gluten-core/src/main/scala/org/apache/gluten/extension/columnar/OffloadSingleNode.scala
index 62c72af792e9..792968cd2ff5 100644
--- a/gluten-core/src/main/scala/org/apache/gluten/extension/columnar/OffloadSingleNode.scala
+++ b/gluten-core/src/main/scala/org/apache/gluten/extension/columnar/OffloadSingleNode.scala
@@ -278,6 +278,17 @@ case class OffloadProject() extends OffloadSingleNode with LogLevelUtil {
         p.copy(genNewProjectList(projectList), addMetadataCol(child, replacedExprs))
       case p @ ProjectExecTransformer(projectList, child) =>
         p.copy(genNewProjectList(projectList), addMetadataCol(child, replacedExprs))
+      case u @ UnionExec(children) =>
+        val newFirstChild = addMetadataCol(children.head, replacedExprs)
+        val newOtherChildren = children.tail.map {
+          child =>
+            // Make sure exprId is unique in each child of Union.
+            val newReplacedExprs = replacedExprs.map {
+              expr => (expr._1, AttributeReference(expr._2.name, expr._2.dataType, false)())
+            }
+            addMetadataCol(child, newReplacedExprs)
+        }
+        u.copy(children = newFirstChild +: newOtherChildren)
       case _ => plan.withNewChildren(plan.children.map(addMetadataCol(_, replacedExprs)))
     }
   }
@@ -299,16 +310,15 @@ case class OffloadProject() extends OffloadSingleNode with LogLevelUtil {
       // Project is still not transformable after remove `input_file_name` expressions.
       projectExec
     } else {
-      // the project with `input_file_name` expression should have at most
-      // one data source, reference:
+      // the project with `input_file_name` expression may have multiple data source
+      // by union all, reference:
       // https://github.com/apache/spark/blob/e459674127e7b21e2767cc62d10ea6f1f941936c
-      // /sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/rules.scala#L506
+      // /sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/rules.scala#L519
       val leafScans = findScanNodes(projectExec)
-      assert(leafScans.size <= 1)
-      if (leafScans.isEmpty || FallbackTags.nonEmpty(leafScans(0))) {
+      if (leafScans.isEmpty || leafScans.exists(FallbackTags.nonEmpty)) {
         // It means
         // 1. projectExec has `input_file_name` but no scan child.
-        // 2. It has scan child node but the scan node fallback.
+        // 2. It has scan children node but the scan node fallback.
         projectExec
       } else {
         val replacedExprs = scala.collection.mutable.Map[String, AttributeReference]()