diff --git a/mem0/configs/vector_stores/opensearch.py b/mem0/configs/vector_stores/opensearch.py
index 2103540ffe..3a24006180 100644
--- a/mem0/configs/vector_stores/opensearch.py
+++ b/mem0/configs/vector_stores/opensearch.py
@@ -14,6 +14,7 @@ class OpenSearchConfig(BaseModel):
     verify_certs: bool = Field(False, description="Verify SSL certificates (default False for OpenSearch)")
     use_ssl: bool = Field(False, description="Use SSL for connection (default False for OpenSearch)")
     auto_create_index: bool = Field(True, description="Automatically create index during initialization")
+    http_auth: Optional[object] = Field(None, description="HTTP authentication method / AWS SigV4")
 
     @model_validator(mode="before")
     @classmethod
@@ -23,7 +24,7 @@ def validate_auth(cls, values: Dict[str, Any]) -> Dict[str, Any]:
             raise ValueError("Host must be provided for OpenSearch")
 
         # Authentication: Either API key or user/password must be provided
-        if not any([values.get("api_key"), (values.get("user") and values.get("password"))]):
+        if not any([values.get("api_key"), (values.get("user") and values.get("password")), values.get("http_auth")]):
             raise ValueError("Either api_key or user/password must be provided for OpenSearch authentication")
 
         return values
diff --git a/mem0/vector_stores/opensearch.py b/mem0/vector_stores/opensearch.py
index 159ec9124c..2a58ac456c 100644
--- a/mem0/vector_stores/opensearch.py
+++ b/mem0/vector_stores/opensearch.py
@@ -2,7 +2,7 @@
 from typing import Any, Dict, List, Optional
 
 try:
-    from opensearchpy import OpenSearch
+    from opensearchpy import OpenSearch, RequestsHttpConnection
     from opensearchpy.helpers import bulk
 except ImportError:
     raise ImportError("OpenSearch requires extra dependencies. Install with `pip install opensearch-py`") from None
@@ -28,9 +28,10 @@ def __init__(self, **kwargs):
         # Initialize OpenSearch client
         self.client = OpenSearch(
             hosts=[{"host": config.host, "port": config.port or 9200}],
-            http_auth=(config.user, config.password) if (config.user and config.password) else None,
+            http_auth=config.http_auth if config.http_auth else ((config.user, config.password) if (config.user and config.password) else None),
             use_ssl=config.use_ssl,
             verify_certs=config.verify_certs,
+            connection_class=RequestsHttpConnection
         )
 
         self.collection_name = config.collection_name
@@ -43,14 +44,17 @@ def __init__(self, **kwargs):
     def create_index(self) -> None:
         """Create OpenSearch index with proper mappings if it doesn't exist."""
         index_settings = {
-            # ToDo change replicas to 1
             "settings": {
                 "index": {"number_of_replicas": 1, "number_of_shards": 5, "refresh_interval": "1s", "knn": True}
             },
             "mappings": {
                 "properties": {
                     "text": {"type": "text"},
-                    "vector": {"type": "knn_vector", "dimension": self.vector_dim},
+                    "vector": {
+                        "type": "knn_vector",
+                        "dimension": self.vector_dim,
+                        "method": {"engine": "lucene", "name": "hnsw", "space_type": "cosinesimil"},
+                    },
                     "metadata": {"type": "object", "properties": {"user_id": {"type": "keyword"}}},
                 }
             },
diff --git a/tests/vector_stores/test_opensearch.py b/tests/vector_stores/test_opensearch.py
index 40d0959ba0..912b660d2a 100644
--- a/tests/vector_stores/test_opensearch.py
+++ b/tests/vector_stores/test_opensearch.py
@@ -5,7 +5,7 @@
 import dotenv
 
 try:
-    from opensearchpy import OpenSearch
+    from opensearchpy import OpenSearch, AWSV4SignerAuth
 except ImportError:
     raise ImportError(
         "OpenSearch requires extra dependencies. Install with `pip install opensearch-py`"
@@ -148,3 +148,29 @@ def test_delete(self):
     def test_delete_col(self):
         self.os_db.delete_col()
         self.client_mock.indices.delete.assert_called_once_with(index="test_collection")
+
+
+    def test_init_with_http_auth(self):
+        mock_credentials = MagicMock()
+        mock_signer = AWSV4SignerAuth(mock_credentials, "us-east-1", "es")
+
+        with patch('mem0.vector_stores.opensearch.OpenSearch') as mock_opensearch:
+            test_db = OpenSearchDB(
+                host="localhost",
+                port=9200,
+                collection_name="test_collection",
+                embedding_model_dims=1536,
+                http_auth=mock_signer,
+                verify_certs=True,
+                use_ssl=True,
+                auto_create_index=False
+            )
+
+            # Verify OpenSearch was initialized with correct params
+            mock_opensearch.assert_called_once_with(
+                hosts=[{"host": "localhost", "port": 9200}],
+                http_auth=mock_signer,
+                use_ssl=True,
+                verify_certs=True,
+                connection_class=unittest.mock.ANY
+            )
\ No newline at end of file