diff --git a/native/core/src/execution/datafusion/planner.rs b/native/core/src/execution/datafusion/planner.rs
index d82c286d4..f5c506688 100644
--- a/native/core/src/execution/datafusion/planner.rs
+++ b/native/core/src/execution/datafusion/planner.rs
@@ -699,17 +699,27 @@ impl PhysicalPlanner {
                 let right =
                     self.create_expr(expr.right.as_ref().unwrap(), Arc::clone(&input_schema))?;
                 let return_type = left.data_type(&input_schema)?;
-                let args = vec![left, right];
+                let args = vec![Arc::clone(&left), right];
                 let datafusion_array_append =
                     Arc::new(ScalarUDF::new_from_impl(ArrayAppend::new()));
-                let scalar_expr: Arc<dyn PhysicalExpr> = Arc::new(ScalarFunctionExpr::new(
+                let array_append_expr: Arc<dyn PhysicalExpr> = Arc::new(ScalarFunctionExpr::new(
                     "array_append",
                     datafusion_array_append,
                     args,
                     return_type,
                 ));
 
-                Ok(scalar_expr)
+                let is_null_expr: Arc<dyn PhysicalExpr> = Arc::new(IsNullExpr::new(left));
+                let null_literal_expr: Arc<dyn PhysicalExpr> =
+                    Arc::new(Literal::new(ScalarValue::Null));
+
+                let case_expr = CaseExpr::try_new(
+                    None,
+                    vec![(is_null_expr, null_literal_expr)],
+                    Some(array_append_expr),
+                )
+                .unwrap();
+                Ok(Arc::new(case_expr))
             }
             expr => Err(ExecutionError::GeneralError(format!(
                 "Not implemented: {:?}",
diff --git a/spark/src/main/scala/org/apache/comet/serde/QueryPlanSerde.scala b/spark/src/main/scala/org/apache/comet/serde/QueryPlanSerde.scala
index d64ee71b9..a5c19eb89 100644
--- a/spark/src/main/scala/org/apache/comet/serde/QueryPlanSerde.scala
+++ b/spark/src/main/scala/org/apache/comet/serde/QueryPlanSerde.scala
@@ -2259,11 +2259,12 @@ object QueryPlanSerde extends Logging with ShimQueryPlanSerde with CometExprShim
             None
           }
         case ArrayAppend(left, right) =>
-          val leftExpr = exprToProto(left, inputs, binding)
-          val rightExpr = exprToProto(right, inputs, binding)
-
-          val optExpr = scalarExprToProto("array_append", leftExpr, rightExpr)
-          optExprWithInfo(optExpr, expr, left, right)
+          createBinaryExpr(left, right, inputs).map { builder =>
+            ExprOuterClass.Expr
+              .newBuilder()
+              .setArrayAppend(builder)
+              .build()
+          }
 
         case _ =>
           withInfo(expr, s"${expr.prettyName} is not supported", expr.children: _*)
diff --git a/spark/src/test/scala/org/apache/comet/CometExpressionSuite.scala b/spark/src/test/scala/org/apache/comet/CometExpressionSuite.scala
index 9466fcd92..9105023c0 100644
--- a/spark/src/test/scala/org/apache/comet/CometExpressionSuite.scala
+++ b/spark/src/test/scala/org/apache/comet/CometExpressionSuite.scala
@@ -2315,6 +2315,7 @@ class CometExpressionSuite extends CometTestBase with AdaptiveSparkPlanHelper {
   }
 
   test("array_append") {
+    assume(isSpark34Plus)
     Seq(true, false).foreach { dictionaryEnabled =>
       withTempDir { dir =>
         val path = new Path(dir.toURI.toString, "test.parquet")
@@ -2328,6 +2329,8 @@ class CometExpressionSuite extends CometTestBase with AdaptiveSparkPlanHelper {
         checkSparkAnswerAndOperator(df.select(array_append(array(col("_6"), col("_7")), 6.5)))
         checkSparkAnswerAndOperator(df.select(array_append(array(col("_8")), "test")))
         checkSparkAnswerAndOperator(df.select(array_append(array(col("_19")), col("_19"))))
+        checkSparkAnswerAndOperator(
+          df.select(array_append(expr("CASE WHEN _2=_3 THEN array(_4) END"), col("_4"))))
       }
     }
   }