diff --git a/cpp/src/arrow/acero/hash_aggregate_test.cc b/cpp/src/arrow/acero/hash_aggregate_test.cc
index 3233441852027..dfeae61a6cda6 100644
--- a/cpp/src/arrow/acero/hash_aggregate_test.cc
+++ b/cpp/src/arrow/acero/hash_aggregate_test.cc
@@ -155,7 +155,7 @@ TEST(AggregateSchema, SingleKeyAndSegmentKey) {
       aggregate::MakeOutputSchema(input_schema, {FieldRef("y")}, {FieldRef("z")},
                                   {{"hash_count", nullptr, "x", "hash_count"}}));
   AssertSchemaEqual(
-      schema({field("y", int32()), field("z", int32()), field("hash_count", int64())}),
+      schema({field("z", int32()), field("y", int32()), field("hash_count", int64())}),
       output_schema);
 }