diff --git a/homeassistant/components/device_automation/__init__.py b/homeassistant/components/device_automation/__init__.py
index 2c6e80e5f49..a75a4216475 100644
--- a/homeassistant/components/device_automation/__init__.py
+++ b/homeassistant/components/device_automation/__init__.py
@@ -484,7 +484,7 @@ async def websocket_device_automation_get_condition_capabilities(
         # The frontend responds with `trigger` as key, while the
         # `DEVICE_TRIGGER_BASE_SCHEMA` expects `platform1` as key.
         vol.Required("trigger"): vol.All(
-            cv._backward_compat_trigger_schema,  # noqa: SLF001
+            cv._trigger_pre_validator,  # noqa: SLF001
             DEVICE_TRIGGER_BASE_SCHEMA.extend({}, extra=vol.ALLOW_EXTRA),
         ),
     }
diff --git a/homeassistant/helpers/config_validation.py b/homeassistant/helpers/config_validation.py
index 8b190abad92..98a2cd71931 100644
--- a/homeassistant/helpers/config_validation.py
+++ b/homeassistant/helpers/config_validation.py
@@ -1771,7 +1771,7 @@ CONDITION_ACTION_SCHEMA: vol.Schema = vol.Schema(
 )
 
 
-def _backward_compat_trigger_schema(value: Any | None) -> Any:
+def _trigger_pre_validator(value: Any | None) -> Any:
     """Rewrite trigger `trigger` to `platform`.
 
     `platform` has been renamed to `trigger` in user documentation and in the automation
@@ -1790,6 +1790,8 @@ def _backward_compat_trigger_schema(value: Any | None) -> Any:
             )
         value = dict(value)
         value[CONF_PLATFORM] = value.pop(CONF_TRIGGER)
+    elif CONF_PLATFORM not in value:
+        raise vol.Invalid("required key not provided", [CONF_TRIGGER])
 
     return value
 
@@ -1831,7 +1833,7 @@ def _base_trigger_validator(value: Any) -> Any:
 TRIGGER_SCHEMA = vol.All(
     ensure_list,
     _base_trigger_list_flatten,
-    [vol.All(_backward_compat_trigger_schema, _base_trigger_validator)],
+    [vol.All(_trigger_pre_validator, _base_trigger_validator)],
 )
 
 _SCRIPT_DELAY_SCHEMA = vol.Schema(
diff --git a/tests/helpers/test_config_validation.py b/tests/helpers/test_config_validation.py
index 4fd87d6d2fe..7202cef6f5f 100644
--- a/tests/helpers/test_config_validation.py
+++ b/tests/helpers/test_config_validation.py
@@ -6,6 +6,7 @@ import enum
 from functools import partial
 import logging
 import os
+import re
 from socket import _GLOBAL_DEFAULT_TIMEOUT
 import threading
 from typing import Any
@@ -1911,16 +1912,19 @@ async def test_nested_trigger_list_extra() -> None:
 async def test_trigger_backwards_compatibility() -> None:
     """Test triggers with backwards compatibility."""
 
-    assert cv._backward_compat_trigger_schema("str") == "str"
-    assert cv._backward_compat_trigger_schema({"platform": "abc"}) == {
-        "platform": "abc"
-    }
-    assert cv._backward_compat_trigger_schema({"trigger": "abc"}) == {"platform": "abc"}
+    assert cv._trigger_pre_validator("str") == "str"
+    assert cv._trigger_pre_validator({"platform": "abc"}) == {"platform": "abc"}
+    assert cv._trigger_pre_validator({"trigger": "abc"}) == {"platform": "abc"}
     with pytest.raises(
         vol.Invalid,
         match="Cannot specify both 'platform' and 'trigger'. Please use 'trigger' only.",
     ):
-        cv._backward_compat_trigger_schema({"trigger": "abc", "platform": "def"})
+        cv._trigger_pre_validator({"trigger": "abc", "platform": "def"})
+    with pytest.raises(
+        vol.Invalid,
+        match=re.escape("required key not provided @ data['trigger']"),
+    ):
+        cv._trigger_pre_validator({})
 
 
 async def test_is_entity_service_schema(