diff --git a/CHANGELOG.md b/CHANGELOG.md
index 97b0e7e40..b10674505 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -38,6 +38,8 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 ### Dependencies
 ### Changed
 - Remove test artifacts from gh_pages workflow ([#335](https://github.com/opensearch-project/opensearch-js/issues/335))
+- Make fields in `BulkOperation` optional to match OpenSearch Bulk API requirements ([#378](https://github.com/opensearch-project/opensearch-js/pull/378))
+
 ### Deprecated
 ### Removed
 ### Fixed
@@ -57,4 +59,4 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 - Fix mutability of connection headers ([#291](https://github.com/opensearch-project/opensearch-js/issues/291))
 
 [2.1]: https://github.com/opensearch-project/opensearch-js/releases/tag/2.1.0
-[Unreleased]: https://github.com/opensearch-project/opensearch-js/compare/2.1...HEAD
\ No newline at end of file
+[Unreleased]: https://github.com/opensearch-project/opensearch-js/compare/2.1...HEAD
diff --git a/api/types.d.ts b/api/types.d.ts
index f0b0fe6e1..6628ce5da 100644
--- a/api/types.d.ts
+++ b/api/types.d.ts
@@ -40,12 +40,12 @@ export interface BulkIndexOperation extends BulkOperation { }
 export interface BulkIndexResponseItem extends BulkResponseItemBase { }
 
 export interface BulkOperation {
-  _id: Id;
-  _index: IndexName;
-  retry_on_conflict: integer;
-  routing: Routing;
-  version: VersionNumber;
-  version_type: VersionType;
+  _id?: Id;
+  _index?: IndexName;
+  retry_on_conflict?: integer;
+  routing?: Routing;
+  version?: VersionNumber;
+  version_type?: VersionType;
 }
 
 export interface BulkOperationContainer {