diff --git a/cpp/src/arrow/acero/hash_aggregate_test.cc b/cpp/src/arrow/acero/hash_aggregate_test.cc
index 9bc370bd3cc28..d529f443319b9 100644
--- a/cpp/src/arrow/acero/hash_aggregate_test.cc
+++ b/cpp/src/arrow/acero/hash_aggregate_test.cc
@@ -595,6 +595,7 @@ void TestSegments(std::unique_ptr<RowSegmenter>& segmenter, const ExecSpan& batc
   // Assert next is the last (empty) segment.
   ASSERT_OK_AND_ASSIGN(auto segment, segmenter->GetNextSegment(batch, offset));
   ASSERT_GE(segment.offset, batch.length);
+  ASSERT_EQ(segment.length, 0);
   ASSERT_TRUE(segment.is_open);
   ASSERT_TRUE(segment.extends);
 }