diff --git a/homeassistant/components/input_datetime/__init__.py b/homeassistant/components/input_datetime/__init__.py
index 2fd52f17a5ed..9d581badd1ac 100644
--- a/homeassistant/components/input_datetime/__init__.py
+++ b/homeassistant/components/input_datetime/__init__.py
@@ -389,7 +389,9 @@ class InputDatetime(collection.CollectionEntity, RestoreEntity):
 
         elif not self.has_time:
             extended = py_datetime.datetime.combine(
-                self._current_datetime, py_datetime.time(0, 0)
+                self._current_datetime,
+                py_datetime.time(0, 0),
+                dt_util.get_default_time_zone(),
             )
             attrs[InputDatetimeEntityStateAttribute.TIMESTAMP] = extended.timestamp()
 
diff --git a/tests/components/input_datetime/test_init.py b/tests/components/input_datetime/test_init.py
index 9e3364ebc424..9c1dad0757f2 100644
--- a/tests/components/input_datetime/test_init.py
+++ b/tests/components/input_datetime/test_init.py
@@ -344,7 +344,9 @@ async def test_set_datetime_date(hass: HomeAssistant) -> None:
     assert not state.attributes["has_time"]
     assert state.attributes["has_date"]
 
-    date_dt_obj = datetime.datetime(2017, 9, 7)
+    date_dt_obj = datetime.datetime(
+        2017, 9, 7, tzinfo=dt_util.get_time_zone(hass.config.time_zone)
+    )
     assert state.attributes["timestamp"] == date_dt_obj.timestamp()