diff --git a/src/agents/extensions/memory/dapr_session.py b/src/agents/extensions/memory/dapr_session.py
index 8d92872406..a425bf866d 100644
--- a/src/agents/extensions/memory/dapr_session.py
+++ b/src/agents/extensions/memory/dapr_session.py
@@ -323,19 +323,49 @@ async def add_items(self, items: list[TResponseInputItem]) -> None:
                         continue
                     raise
 
-            # Update metadata
-            metadata = {
-                "session_id": self.session_id,
-                "created_at": str(int(time.time())),
-                "updated_at": str(int(time.time())),
-            }
-            await self._dapr_client.save_state(
-                store_name=self._state_store_name,
-                key=self._metadata_key,
-                value=json.dumps(metadata),
-                state_metadata=self._get_metadata(),
-                options=self._get_state_options(),
-            )
+            # Update metadata, preserving created_at across subsequent writes.
+            # Use first-write concurrency with the read ETag so a concurrent write
+            # that already established `created_at` can't be clobbered by a stale
+            # read that saw no metadata.
+            now = str(int(time.time()))
+            meta_attempt = 0
+            while True:
+                meta_attempt += 1
+                existing_meta_response = await self._dapr_client.get_state(
+                    store_name=self._state_store_name,
+                    key=self._metadata_key,
+                    state_metadata=self._get_read_metadata(),
+                )
+                created_at = now
+                if existing_meta_response.data:
+                    try:
+                        existing_meta = json.loads(existing_meta_response.data.decode("utf-8"))
+                        if isinstance(existing_meta, dict) and existing_meta.get("created_at"):
+                            created_at = str(existing_meta["created_at"])
+                    except (json.JSONDecodeError, UnicodeDecodeError, AttributeError):
+                        # Corrupt metadata — start fresh with current timestamp.
+                        pass
+                metadata = {
+                    "session_id": self.session_id,
+                    "created_at": created_at,
+                    "updated_at": now,
+                }
+                meta_etag = getattr(existing_meta_response, "etag", None) or None
+                try:
+                    await self._dapr_client.save_state(
+                        store_name=self._state_store_name,
+                        key=self._metadata_key,
+                        value=json.dumps(metadata),
+                        etag=meta_etag,
+                        state_metadata=self._get_metadata(),
+                        options=self._get_state_options(concurrency=Concurrency.first_write),
+                    )
+                    break
+                except Exception as error:
+                    should_retry = await self._handle_concurrency_conflict(error, meta_attempt)
+                    if should_retry:
+                        continue
+                    raise
 
     async def pop_item(self) -> TResponseInputItem | None:
         """Remove and return the most recent item from the session.
diff --git a/tests/extensions/memory/test_dapr_session.py b/tests/extensions/memory/test_dapr_session.py
index 9766f35d40..f2dff71561 100644
--- a/tests/extensions/memory/test_dapr_session.py
+++ b/tests/extensions/memory/test_dapr_session.py
@@ -448,6 +448,32 @@ async def test_add_empty_items_list(fake_dapr_client: FakeDaprClient):
         await session.close()
 
 
+async def test_metadata_preserves_created_at(fake_dapr_client: FakeDaprClient):
+    """add_items must preserve created_at across writes; only updated_at advances."""
+    session = await _create_test_session(fake_dapr_client)
+    try:
+        await session.add_items([{"role": "user", "content": "first"}])
+        first_meta_raw = fake_dapr_client._state[session._metadata_key].decode("utf-8")
+        first_meta = json.loads(first_meta_raw)
+        first_created = first_meta["created_at"]
+        first_updated = first_meta["updated_at"]
+
+        # Wait one second so timestamps are guaranteed to differ.
+        import time as _time
+
+        _time.sleep(1)
+
+        await session.add_items([{"role": "user", "content": "second"}])
+        second_meta = json.loads(fake_dapr_client._state[session._metadata_key].decode("utf-8"))
+
+        assert second_meta["created_at"] == first_created, (
+            "created_at must be preserved across add_items calls"
+        )
+        assert int(second_meta["updated_at"]) >= int(first_updated)
+    finally:
+        await session.close()
+
+
 async def test_unicode_content(fake_dapr_client: FakeDaprClient):
     """Test that session correctly stores and retrieves unicode/non-ASCII content."""
     session = await _create_test_session(fake_dapr_client)