diff --git a/CHANGELOG.md b/CHANGELOG.md
index 8aae7e84c..43c0a6e7f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -30,6 +30,7 @@ Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 - Added schema for `/_plugins/_knn/stats`, `/_plugins/_knn/models/{model_id}`, `_train` and `_search` ([#704](https://github.com/opensearch-project/opensearch-api-specification/pull/704))
 - Added `retry` support in `prologues` and `epilogues` ([#713](https://github.com/opensearch-project/opensearch-api-specification/pull/713))
 - Added response schema for `DELETE /_plugins/_rollup/jobs/{id}`, `POST /_plugins/_rollup/jobs/{id}/_start` and `_stop` ([#716](https://github.com/opensearch-project/opensearch-api-specification/pull/716))
+- Added response schema for `GET /_plugins/_knn/warmup/{index}` ([#717](https://github.com/opensearch-project/opensearch-api-specification/pull/717))
 
 ### Removed
 - Removed unsupported `_common.mapping:SourceField`'s `mode` field and associated `_common.mapping:SourceFieldMode` enum ([#652](https://github.com/opensearch-project/opensearch-api-specification/pull/652))
diff --git a/spec/namespaces/knn.yaml b/spec/namespaces/knn.yaml
index d7156d4b9..c547a7894 100644
--- a/spec/namespaces/knn.yaml
+++ b/spec/namespaces/knn.yaml
@@ -283,7 +283,11 @@ components:
                 type: string
             required:
               - model_id
-    knn.warmup@200: {}
+    knn.warmup@200:
+      content:
+        application/json:
+          schema:
+            $ref: '../schemas/_common.yaml#/components/schemas/ShardsOperationResponseBase'
   parameters:
     knn.delete_model::path.model_id:
       name: model_id
diff --git a/tests/default/knn/warmup.yaml b/tests/default/knn/warmup.yaml
new file mode 100644
index 000000000..656e67ee6
--- /dev/null
+++ b/tests/default/knn/warmup.yaml
@@ -0,0 +1,30 @@
+$schema: ../../../json_schemas/test_story.schema.yaml
+
+description: Load all the native library files for all the shards into native memory.
+prologues:
+  - method: PUT
+    path: /movies
+    request:
+      payload:
+        settings:
+          index:
+            knn: true
+        mappings:
+          properties:
+            recommendation_vector:
+              type: knn_vector
+              dimension: 8
+    status: [200]
+epilogues:
+  - path: /movies
+    method: DELETE
+    status: [200, 404]
+chapters:
+  - synopsis: Warmup an index.
+    method: GET
+    path: /_plugins/_knn/warmup/{index}
+    parameters:
+      index:
+        - movies
+    response:
+      status: 200