diff --git a/homeassistant/components/input_datetime/__init__.py b/homeassistant/components/input_datetime/__init__.py
index aa1f0b8814a..195e4c2242e 100644
--- a/homeassistant/components/input_datetime/__init__.py
+++ b/homeassistant/components/input_datetime/__init__.py
@@ -365,9 +365,7 @@ class InputDatetime(RestoreEntity):
     def async_set_datetime(self, date=None, time=None, datetime=None, timestamp=None):
         """Set a new date / time."""
         if timestamp:
-            datetime = dt_util.as_local(dt_util.utc_from_timestamp(timestamp)).replace(
-                tzinfo=None
-            )
+            datetime = dt_util.as_local(dt_util.utc_from_timestamp(timestamp))
 
         if datetime:
             date = datetime.date()
@@ -388,8 +386,8 @@ class InputDatetime(RestoreEntity):
         if not time:
             time = self._current_datetime.time()
 
-        self._current_datetime = py_datetime.datetime.combine(date, time).replace(
-            tzinfo=dt_util.DEFAULT_TIME_ZONE
+        self._current_datetime = dt_util.DEFAULT_TIME_ZONE.localize(
+            py_datetime.datetime.combine(date, time)
         )
         self.async_write_ha_state()
 
diff --git a/tests/components/input_datetime/test_init.py b/tests/components/input_datetime/test_init.py
index d40a88e3f43..a336ef82363 100644
--- a/tests/components/input_datetime/test_init.py
+++ b/tests/components/input_datetime/test_init.py
@@ -697,6 +697,15 @@ async def test_timestamp(hass):
             ).strftime(FMT_DATETIME)
             == "2020-12-13 10:00:00"
         )
+        # Use datetime.datetime.fromtimestamp
+        assert (
+            dt_util.as_local(
+                datetime.datetime.fromtimestamp(
+                    state_without_tz.attributes[ATTR_TIMESTAMP]
+                )
+            ).strftime(FMT_DATETIME)
+            == "2020-12-13 10:00:00"
+        )
 
         # Test initial time sets timestamp correctly.
         state_time = hass.states.get("input_datetime.test_time_initial")
@@ -704,5 +713,24 @@ async def test_timestamp(hass):
         assert state_time.state == "10:00:00"
         assert state_time.attributes[ATTR_TIMESTAMP] == 10 * 60 * 60
 
+        # Test that setting the timestamp of an entity works.
+        await hass.services.async_call(
+            DOMAIN,
+            "set_datetime",
+            {
+                ATTR_ENTITY_ID: "input_datetime.test_datetime_initial_with_tz",
+                ATTR_TIMESTAMP: state_without_tz.attributes[ATTR_TIMESTAMP],
+            },
+            blocking=True,
+        )
+        state_with_tz_updated = hass.states.get(
+            "input_datetime.test_datetime_initial_with_tz"
+        )
+        assert state_with_tz_updated.state == "2020-12-13 10:00:00"
+        assert (
+            state_with_tz_updated.attributes[ATTR_TIMESTAMP]
+            == state_without_tz.attributes[ATTR_TIMESTAMP]
+        )
+
     finally:
         dt_util.set_default_time_zone(ORIG_TIMEZONE)