diff --git a/haystack/document_stores/opensearch.py b/haystack/document_stores/opensearch.py
index ff54efb14..6f402498d 100644
--- a/haystack/document_stores/opensearch.py
+++ b/haystack/document_stores/opensearch.py
@@ -745,10 +745,11 @@ class OpenSearchDocumentStore(SearchEngineDocumentStore):
         :return: None
         """
         # Check if index uses an IVF model and delete it
-        index_mapping = self.client.indices.get(index)[index]["mappings"]["properties"]
-        if self.embedding_field in index_mapping and "model_id" in index_mapping[self.embedding_field]:
-            model_id = index_mapping[self.embedding_field]["model_id"]
-            self.client.transport.perform_request("DELETE", f"/_plugins/_knn/models/{model_id}")
+        if self._index_exists(index):
+            index_mapping = self.client.indices.get(index)[index]["mappings"]["properties"]
+            if self.embedding_field in index_mapping and "model_id" in index_mapping[self.embedding_field]:
+                model_id = index_mapping[self.embedding_field]["model_id"]
+                self.client.transport.perform_request("DELETE", f"/_plugins/_knn/models/{model_id}")
 
         super().delete_index(index)
 
diff --git a/haystack/testing/document_store.py b/haystack/testing/document_store.py
index 8a307f5a6..6e12da675 100644
--- a/haystack/testing/document_store.py
+++ b/haystack/testing/document_store.py
@@ -478,6 +478,10 @@ class DocumentStoreBaseTestAbstract:
         with pytest.raises(Exception):
             ds.get_document_count(index="custom_index")
 
+    @pytest.mark.integration
+    def test_delete_index_does_not_raise_if_not_exists(self, ds):
+        ds.delete_index(index="unknown_index")
+
     @pytest.mark.integration
     def test_update_meta(self, ds, documents):
         ds.write_documents(documents)