diff --git a/homeassistant/components/matter/select.py b/homeassistant/components/matter/select.py
index b46cad53123..2e9c44a8f8a 100644
--- a/homeassistant/components/matter/select.py
+++ b/homeassistant/components/matter/select.py
@@ -229,18 +229,18 @@ DISCOVERY_SCHEMAS = [
             entity_category=EntityCategory.CONFIG,
             translation_key="startup_on_off",
             options=["On", "Off", "Toggle", "Previous"],
-            measurement_to_ha=lambda x: {  # pylint: disable=unnecessary-lambda
+            measurement_to_ha={
                 0: "Off",
                 1: "On",
                 2: "Toggle",
                 None: "Previous",
-            }.get(x),
-            ha_to_native_value=lambda x: {
+            }.get,
+            ha_to_native_value={
                 "Off": 0,
                 "On": 1,
                 "Toggle": 2,
                 "Previous": None,
-            }[x],
+            }.get,
         ),
         entity_class=MatterSelectEntity,
         required_attributes=(clusters.OnOff.Attributes.StartUpOnOff,),
diff --git a/tests/components/matter/test_select.py b/tests/components/matter/test_select.py
index f84e5870392..e380e5d5925 100644
--- a/tests/components/matter/test_select.py
+++ b/tests/components/matter/test_select.py
@@ -97,3 +97,8 @@ async def test_attribute_select_entities(
     await trigger_subscription_callback(hass, matter_client)
     state = hass.states.get(entity_id)
     assert state.state == "On"
+    # test that an invalid value (e.g. 255) leads to an unknown state
+    set_node_attribute(light_node, 1, 6, 16387, 255)
+    await trigger_subscription_callback(hass, matter_client)
+    state = hass.states.get(entity_id)
+    assert state.state == "unknown"