diff --git a/homeassistant/components/geo_location/__init__.py b/homeassistant/components/geo_location/__init__.py
index e58391ca84a..54542fa8503 100644
--- a/homeassistant/components/geo_location/__init__.py
+++ b/homeassistant/components/geo_location/__init__.py
@@ -3,7 +3,7 @@ from __future__ import annotations
 
 from datetime import timedelta
 import logging
-from typing import final
+from typing import Any, final
 
 from homeassistant.config_entries import ConfigEntry
 from homeassistant.const import ATTR_LATITUDE, ATTR_LONGITUDE
@@ -54,8 +54,15 @@ async def async_unload_entry(hass: HomeAssistant, entry: ConfigEntry) -> bool:
 class GeolocationEvent(Entity):
     """Base class for an external event with an associated geolocation."""
 
+    # Entity Properties
+    _attr_source: str
+    _attr_distance: float | None = None
+    _attr_latitude: float | None = None
+    _attr_longitude: float | None = None
+
+    @final
     @property
-    def state(self):
+    def state(self) -> float | None:
         """Return the state of the sensor."""
         if self.distance is not None:
             return round(self.distance, 1)
@@ -64,32 +71,30 @@ class GeolocationEvent(Entity):
     @property
     def source(self) -> str:
         """Return source value of this external event."""
-        raise NotImplementedError
+        return self._attr_source
 
     @property
     def distance(self) -> float | None:
         """Return distance value of this external event."""
-        return None
+        return self._attr_distance
 
     @property
     def latitude(self) -> float | None:
         """Return latitude value of this external event."""
-        return None
+        return self._attr_latitude
 
     @property
     def longitude(self) -> float | None:
         """Return longitude value of this external event."""
-        return None
+        return self._attr_longitude
 
     @final
     @property
-    def state_attributes(self):
+    def state_attributes(self) -> dict[str, Any]:
         """Return the state attributes of this external event."""
-        data = {}
+        data: dict[str, Any] = {ATTR_SOURCE: self.source}
         if self.latitude is not None:
             data[ATTR_LATITUDE] = round(self.latitude, 5)
         if self.longitude is not None:
             data[ATTR_LONGITUDE] = round(self.longitude, 5)
-        if self.source is not None:
-            data[ATTR_SOURCE] = self.source
         return data
diff --git a/tests/components/geo_location/test_init.py b/tests/components/geo_location/test_init.py
index 00cb2a872d2..f2cb5c6b108 100644
--- a/tests/components/geo_location/test_init.py
+++ b/tests/components/geo_location/test_init.py
@@ -20,5 +20,5 @@ async def test_event(hass):
     assert entity.distance is None
     assert entity.latitude is None
     assert entity.longitude is None
-    with pytest.raises(NotImplementedError):
+    with pytest.raises(AttributeError):
         assert entity.source is None