diff --git a/homeassistant/config.py b/homeassistant/config.py
index 0f68e0bd235..e71b0dcd726 100644
--- a/homeassistant/config.py
+++ b/homeassistant/config.py
@@ -46,7 +46,6 @@ from .const import (
     CONF_UNIT_SYSTEM,
     CONF_UNIT_SYSTEM_IMPERIAL,
     LEGACY_CONF_WHITELIST_EXTERNAL_DIRS,
-    TEMP_CELSIUS,
     __version__,
 )
 from .core import DOMAIN as CONF_CORE, ConfigSource, HomeAssistant, callback
@@ -204,7 +203,7 @@ CORE_CONFIG_SCHEMA = vol.All(
             CONF_LATITUDE: cv.latitude,
             CONF_LONGITUDE: cv.longitude,
             CONF_ELEVATION: vol.Coerce(int),
-            vol.Optional(CONF_TEMPERATURE_UNIT): cv.temperature_unit,
+            vol.Remove(CONF_TEMPERATURE_UNIT): cv.temperature_unit,
             CONF_UNIT_SYSTEM: cv.unit_system,
             CONF_TIME_ZONE: cv.time_zone,
             vol.Optional(CONF_INTERNAL_URL): cv.url,
@@ -607,18 +606,6 @@ async def async_process_ha_core_config(hass: HomeAssistant, config: dict) -> Non
             hac.units = IMPERIAL_SYSTEM
         else:
             hac.units = METRIC_SYSTEM
-    elif CONF_TEMPERATURE_UNIT in config:
-        unit = config[CONF_TEMPERATURE_UNIT]
-        hac.units = METRIC_SYSTEM if unit == TEMP_CELSIUS else IMPERIAL_SYSTEM
-        _LOGGER.warning(
-            "Found deprecated temperature unit in core "
-            "configuration expected unit system. Replace '%s: %s' "
-            "with '%s: %s'",
-            CONF_TEMPERATURE_UNIT,
-            unit,
-            CONF_UNIT_SYSTEM,
-            hac.units.name,
-        )
 
 
 def _log_pkg_error(package: str, component: str, config: dict, message: str) -> None:
diff --git a/tests/test_config.py b/tests/test_config.py
index 9b3f9d8755f..15c5f84bc42 100644
--- a/tests/test_config.py
+++ b/tests/test_config.py
@@ -22,7 +22,6 @@ from homeassistant.const import (
     CONF_LATITUDE,
     CONF_LONGITUDE,
     CONF_NAME,
-    CONF_TEMPERATURE_UNIT,
     CONF_UNIT_SYSTEM,
     CONF_UNIT_SYSTEM_IMPERIAL,
     CONF_UNIT_SYSTEM_METRIC,
@@ -538,34 +537,6 @@ async def test_loading_configuration(hass):
     assert hass.config.currency == "EUR"
 
 
-async def test_loading_configuration_temperature_unit(hass):
-    """Test backward compatibility when loading core config."""
-    await config_util.async_process_ha_core_config(
-        hass,
-        {
-            "latitude": 60,
-            "longitude": 50,
-            "elevation": 25,
-            "name": "Huis",
-            CONF_TEMPERATURE_UNIT: "C",
-            "time_zone": "America/New_York",
-            "external_url": "https://www.example.com",
-            "internal_url": "http://example.local",
-        },
-    )
-
-    assert hass.config.latitude == 60
-    assert hass.config.longitude == 50
-    assert hass.config.elevation == 25
-    assert hass.config.location_name == "Huis"
-    assert hass.config.units.name == CONF_UNIT_SYSTEM_METRIC
-    assert hass.config.time_zone == "America/New_York"
-    assert hass.config.external_url == "https://www.example.com"
-    assert hass.config.internal_url == "http://example.local"
-    assert hass.config.config_source is ConfigSource.YAML
-    assert hass.config.currency == "EUR"
-
-
 async def test_loading_configuration_default_media_dirs_docker(hass):
     """Test loading core config onto hass object."""
     with patch("homeassistant.config.is_docker_env", return_value=True):
@@ -591,7 +562,7 @@ async def test_loading_configuration_from_packages(hass):
             "longitude": -1,
             "elevation": 500,
             "name": "Huis",
-            CONF_TEMPERATURE_UNIT: "C",
+            CONF_UNIT_SYSTEM: CONF_UNIT_SYSTEM_METRIC,
             "time_zone": "Europe/Madrid",
             "external_url": "https://www.example.com",
             "internal_url": "http://example.local",
@@ -615,7 +586,7 @@ async def test_loading_configuration_from_packages(hass):
                 "longitude": -1,
                 "elevation": 500,
                 "name": "Huis",
-                CONF_TEMPERATURE_UNIT: "C",
+                CONF_UNIT_SYSTEM: CONF_UNIT_SYSTEM_METRIC,
                 "time_zone": "Europe/Madrid",
                 "packages": {"empty_package": None},
             },