diff --git a/homeassistant/components/knx/binary_sensor.py b/homeassistant/components/knx/binary_sensor.py
index 5ed0e55765d..b4e3354fc37 100644
--- a/homeassistant/components/knx/binary_sensor.py
+++ b/homeassistant/components/knx/binary_sensor.py
@@ -19,9 +19,8 @@ from homeassistant.core import HomeAssistant
 from homeassistant.helpers.entity_platform import AddEntitiesCallback
 from homeassistant.helpers.restore_state import RestoreEntity
 from homeassistant.helpers.typing import ConfigType, DiscoveryInfoType
-from homeassistant.util import dt
 
-from .const import ATTR_COUNTER, ATTR_LAST_KNX_UPDATE, ATTR_SOURCE, DOMAIN
+from .const import ATTR_COUNTER, ATTR_SOURCE, DOMAIN
 from .knx_entity import KnxEntity
 from .schema import BinarySensorSchema
 
@@ -92,7 +91,4 @@ class KNXBinarySensor(KnxEntity, BinarySensorEntity, RestoreEntity):
             attr[ATTR_COUNTER] = self._device.counter
         if self._device.last_telegram is not None:
             attr[ATTR_SOURCE] = str(self._device.last_telegram.source_address)
-            attr[ATTR_LAST_KNX_UPDATE] = str(
-                dt.as_utc(self._device.last_telegram.timestamp)
-            )
         return attr
diff --git a/homeassistant/components/knx/const.py b/homeassistant/components/knx/const.py
index 421297da9d6..7eae5f1c19f 100644
--- a/homeassistant/components/knx/const.py
+++ b/homeassistant/components/knx/const.py
@@ -37,7 +37,6 @@ CONF_STATE_ADDRESS: Final = "state_address"
 CONF_SYNC_STATE: Final = "sync_state"
 
 ATTR_COUNTER: Final = "counter"
-ATTR_LAST_KNX_UPDATE: Final = "last_knx_update"
 ATTR_SOURCE: Final = "source"
 
 
diff --git a/homeassistant/components/knx/sensor.py b/homeassistant/components/knx/sensor.py
index fb64f65968b..84f535fdc8f 100644
--- a/homeassistant/components/knx/sensor.py
+++ b/homeassistant/components/knx/sensor.py
@@ -15,9 +15,8 @@ from homeassistant.const import CONF_ENTITY_CATEGORY, CONF_NAME, CONF_TYPE
 from homeassistant.core import HomeAssistant
 from homeassistant.helpers.entity_platform import AddEntitiesCallback
 from homeassistant.helpers.typing import ConfigType, DiscoveryInfoType, StateType
-from homeassistant.util import dt
 
-from .const import ATTR_LAST_KNX_UPDATE, ATTR_SOURCE, DOMAIN
+from .const import ATTR_SOURCE, DOMAIN
 from .knx_entity import KnxEntity
 from .schema import SensorSchema
 
@@ -82,7 +81,4 @@ class KNXSensor(KnxEntity, SensorEntity):
 
         if self._device.last_telegram is not None:
             attr[ATTR_SOURCE] = str(self._device.last_telegram.source_address)
-            attr[ATTR_LAST_KNX_UPDATE] = str(
-                dt.as_utc(self._device.last_telegram.timestamp)
-            )
         return attr