diff --git a/homeassistant/components/mqtt/lock.py b/homeassistant/components/mqtt/lock.py
index b565e8a4b57..9a0ce2077f3 100644
--- a/homeassistant/components/mqtt/lock.py
+++ b/homeassistant/components/mqtt/lock.py
@@ -28,6 +28,7 @@ from .const import (
     CONF_COMMAND_TEMPLATE,
     CONF_COMMAND_TOPIC,
     CONF_ENCODING,
+    CONF_PAYLOAD_RESET,
     CONF_QOS,
     CONF_RETAIN,
     CONF_STATE_TOPIC,
@@ -63,6 +64,7 @@ DEFAULT_NAME = "MQTT Lock"
 DEFAULT_PAYLOAD_LOCK = "LOCK"
 DEFAULT_PAYLOAD_UNLOCK = "UNLOCK"
 DEFAULT_PAYLOAD_OPEN = "OPEN"
+DEFAULT_PAYLOAD_RESET = "None"
 DEFAULT_STATE_LOCKED = "LOCKED"
 DEFAULT_STATE_LOCKING = "LOCKING"
 DEFAULT_STATE_UNLOCKED = "UNLOCKED"
@@ -84,6 +86,7 @@ PLATFORM_SCHEMA_MODERN = MQTT_RW_SCHEMA.extend(
         vol.Optional(CONF_PAYLOAD_LOCK, default=DEFAULT_PAYLOAD_LOCK): cv.string,
         vol.Optional(CONF_PAYLOAD_UNLOCK, default=DEFAULT_PAYLOAD_UNLOCK): cv.string,
         vol.Optional(CONF_PAYLOAD_OPEN): cv.string,
+        vol.Optional(CONF_PAYLOAD_RESET, default=DEFAULT_PAYLOAD_RESET): cv.string,
         vol.Optional(CONF_STATE_JAMMED, default=DEFAULT_STATE_JAMMED): cv.string,
         vol.Optional(CONF_STATE_LOCKED, default=DEFAULT_STATE_LOCKED): cv.string,
         vol.Optional(CONF_STATE_LOCKING, default=DEFAULT_STATE_LOCKING): cv.string,
@@ -197,8 +200,12 @@ class MqttLock(MqttEntity, LockEntity):
         )
         def message_received(msg: ReceiveMessage) -> None:
             """Handle new lock state messages."""
-            payload = self._value_template(msg.payload)
-            if payload in self._valid_states:
+            if (payload := self._value_template(msg.payload)) == self._config[
+                CONF_PAYLOAD_RESET
+            ]:
+                # Reset the state to `unknown`
+                self._attr_is_locked = None
+            elif payload in self._valid_states:
                 self._attr_is_locked = payload == self._config[CONF_STATE_LOCKED]
                 self._attr_is_locking = payload == self._config[CONF_STATE_LOCKING]
                 self._attr_is_unlocking = payload == self._config[CONF_STATE_UNLOCKING]
diff --git a/tests/components/mqtt/test_lock.py b/tests/components/mqtt/test_lock.py
index 0045e003804..e128590c907 100644
--- a/tests/components/mqtt/test_lock.py
+++ b/tests/components/mqtt/test_lock.py
@@ -126,6 +126,7 @@ async def test_controlling_state_via_topic(
         (CONFIG_WITH_STATES, "closing", STATE_LOCKING),
         (CONFIG_WITH_STATES, "open", STATE_UNLOCKED),
         (CONFIG_WITH_STATES, "opening", STATE_UNLOCKING),
+        (CONFIG_WITH_STATES, "None", STATE_UNKNOWN),
     ],
 )
 async def test_controlling_non_default_state_via_topic(
@@ -186,6 +187,15 @@ async def test_controlling_non_default_state_via_topic(
             '{"val":"open"}',
             STATE_UNLOCKED,
         ),
+        (
+            help_custom_config(
+                lock.DOMAIN,
+                CONFIG_WITH_STATES,
+                ({"value_template": "{{ value_json.val }}"},),
+            ),
+            '{"val":null}',
+            STATE_UNKNOWN,
+        ),
     ],
 )
 async def test_controlling_state_via_topic_and_json_message(