diff --git a/CHANGELOG.md b/CHANGELOG.md
index b0eed26bb9..585fb4d433 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -57,6 +57,7 @@ This section is for maintaining a changelog for all breaking changes for the cli
 - Fixed don't invoke the mapper's serialize method for the RangeQuery JsonData raw value ([#1309](https://github.com/opensearch-project/opensearch-java/pull/1309))
 - Fixed `GetSnapshotResponse` deserialization ([#1299](https://github.com/opensearch-project/opensearch-java/pull/1299))
 - Fixed `CreateSnapshotResponse` deserialization when wait_for_completion is false  ([#1332](https://github.com/opensearch-project/opensearch-java/pull/1332))
+- Fixed serialization of nested aggregates under `SingleBucketAggregateBase` ([#1350](https://github.com/opensearch-project/opensearch-java/pull/1350))
 
 ### Security
 
diff --git a/java-client/src/main/java/org/opensearch/client/opensearch/_types/aggregations/SingleBucketAggregateBase.java b/java-client/src/main/java/org/opensearch/client/opensearch/_types/aggregations/SingleBucketAggregateBase.java
index 35ade2fbb9..d96f002654 100644
--- a/java-client/src/main/java/org/opensearch/client/opensearch/_types/aggregations/SingleBucketAggregateBase.java
+++ b/java-client/src/main/java/org/opensearch/client/opensearch/_types/aggregations/SingleBucketAggregateBase.java
@@ -37,6 +37,7 @@
 import java.util.Map;
 import java.util.function.Function;
 import javax.annotation.Nullable;
+import org.opensearch.client.json.ExternallyTaggedUnion;
 import org.opensearch.client.json.JsonpDeserializer;
 import org.opensearch.client.json.JsonpMapper;
 import org.opensearch.client.json.ObjectDeserializer;
@@ -71,8 +72,10 @@ public final long docCount() {
     }
 
     protected void serializeInternal(JsonGenerator generator, JsonpMapper mapper) {
-
         super.serializeInternal(generator, mapper);
+
+        ExternallyTaggedUnion.serializeTypedKeysInner(this.aggregations, generator, mapper);
+
         generator.writeKey("doc_count");
         generator.write(this.docCount);