diff --git a/src/google/adk/cli/adk_web_server.py b/src/google/adk/cli/adk_web_server.py
index e990015c76..3a81d2ae02 100644
--- a/src/google/adk/cli/adk_web_server.py
+++ b/src/google/adk/cli/adk_web_server.py
@@ -31,6 +31,7 @@
 from fastapi import FastAPI
 from fastapi import HTTPException
 from fastapi import Query
+from fastapi import Response
 from fastapi.middleware.cors import CORSMiddleware
 from fastapi.responses import RedirectResponse
 from fastapi.responses import StreamingResponse
@@ -210,6 +211,13 @@ class RunEvalRequest(common.BaseModel):
   eval_metrics: list[EvalMetric]
 
 
+class UpdateMemoryRequest(common.BaseModel):
+  """Request to add a session to the memory service."""
+
+  session_id: str
+  """The ID of the session to add to memory."""
+
+
 class RunEvalResult(common.BaseModel):
   eval_set_file: str
   eval_set_id: str
@@ -1144,6 +1152,41 @@ async def delete_artifact(
           filename=artifact_name,
       )
 
+    @app.patch("/apps/{app_name}/users/{user_id}/memory")
+    async def patch_memory(
+        app_name: str, user_id: str, update_memory_request: UpdateMemoryRequest
+    ) -> None:
+      """Adds all events from a given session to the memory service.
+
+      Args:
+          app_name: The name of the application.
+          user_id: The ID of the user.
+          update_memory_request: The memory request for the update
+
+      Raises:
+          HTTPException: If the memory service is not configured or the request is invalid.
+      """
+      if not self.memory_service:
+        raise HTTPException(
+            status_code=400, detail="Memory service is not configured."
+        )
+      if (
+          update_memory_request is None
+          or update_memory_request.session_id is None
+      ):
+        raise HTTPException(
+            status_code=400, detail="Update memory request is invalid."
+        )
+
+      session = await self.session_service.get_session(
+          app_name=app_name,
+          user_id=user_id,
+          session_id=update_memory_request.session_id,
+      )
+      if not session:
+        raise HTTPException(status_code=404, detail="Session not found")
+      await self.memory_service.add_session_to_memory(session)
+
     @app.post("/run", response_model_exclude_none=True)
     async def run_agent(req: RunAgentRequest) -> list[Event]:
       session = await self.session_service.get_session(
diff --git a/tests/unittests/cli/test_fast_api.py b/tests/unittests/cli/test_fast_api.py
index d1e8dcabc2..4bcf2f119f 100755
--- a/tests/unittests/cli/test_fast_api.py
+++ b/tests/unittests/cli/test_fast_api.py
@@ -22,6 +22,7 @@
 import time
 from typing import Any
 from typing import Optional
+from unittest.mock import AsyncMock
 from unittest.mock import MagicMock
 from unittest.mock import patch
 
@@ -344,7 +345,7 @@ async def delete_artifact(self, app_name, user_id, session_id, filename):
 @pytest.fixture
 def mock_memory_service():
   """Create a mock memory service."""
-  return MagicMock()
+  return AsyncMock()
 
 
 @pytest.fixture
@@ -939,5 +940,18 @@ def test_a2a_disabled_by_default(test_app):
   logger.info("A2A disabled by default test passed")
 
 
+def test_patch_memory(test_app, create_test_session, mock_memory_service):
+  """Test adding a session to memory."""
+  info = create_test_session
+  url = f"/apps/{info['app_name']}/users/{info['user_id']}/memory"
+  payload = {"session_id": info["session_id"]}
+  response = test_app.patch(url, json=payload)
+
+  # Verify the response
+  assert response.status_code == 200
+  mock_memory_service.add_session_to_memory.assert_called_once()
+  logger.info("Add session to memory test completed successfully")
+
+
 if __name__ == "__main__":
   pytest.main(["-xvs", __file__])