diff --git a/tests/components/notify/test_init.py b/tests/components/notify/test_init.py
index 26ed2ddc250..1f9ec81e36a 100644
--- a/tests/components/notify/test_init.py
+++ b/tests/components/notify/test_init.py
@@ -7,6 +7,7 @@ from typing import Any
 from unittest.mock import MagicMock, Mock, patch
 
 import pytest
+import voluptuous as vol
 import yaml
 
 from homeassistant import config as hass_config
@@ -120,6 +121,27 @@ async def test_send_message_service(
     await hass.async_block_till_done()
 
     entity.send_message_mock_calls.assert_called_once()
+    entity.send_message_mock_calls.reset_mock()
+
+    # Test schema: `None` message fails
+    with pytest.raises(vol.Invalid) as exc:
+        await hass.services.async_call(
+            notify.DOMAIN,
+            notify.SERVICE_SEND_MESSAGE,
+            {"entity_id": "notify.test", notify.ATTR_MESSAGE: None},
+        )
+    assert (
+        str(exc.value) == "string value is None for dictionary value @ data['message']"
+    )
+    entity.send_message_mock_calls.assert_not_called()
+
+    # Test schema: No message fails
+    with pytest.raises(vol.Invalid) as exc:
+        await hass.services.async_call(
+            notify.DOMAIN, notify.SERVICE_SEND_MESSAGE, {"entity_id": "notify.test"}
+        )
+    assert str(exc.value) == "required key not provided @ data['message']"
+    entity.send_message_mock_calls.assert_not_called()
 
     # Test unloading the entry succeeds
     assert await hass.config_entries.async_unload(config_entry.entry_id)