diff --git a/homeassistant/components/google_assistant/trait.py b/homeassistant/components/google_assistant/trait.py
index d32dd91a3c1..e0d12e00e30 100644
--- a/homeassistant/components/google_assistant/trait.py
+++ b/homeassistant/components/google_assistant/trait.py
@@ -197,6 +197,8 @@ class OnOffTrait(_Trait):
     @staticmethod
     def supported(domain, features):
         """Test if state is supported."""
+        if domain == climate.DOMAIN:
+            return features & climate.SUPPORT_ON_OFF != 0
         return domain in (
             group.DOMAIN,
             input_boolean.DOMAIN,
diff --git a/tests/components/google_assistant/__init__.py b/tests/components/google_assistant/__init__.py
index 1568919a9b4..c8748ade00e 100644
--- a/tests/components/google_assistant/__init__.py
+++ b/tests/components/google_assistant/__init__.py
@@ -225,7 +225,10 @@ DEMO_DEVICES = [{
     'name': {
         'name': 'HeatPump'
     },
-    'traits': ['action.devices.traits.TemperatureSetting'],
+    'traits': [
+        'action.devices.traits.OnOff',
+        'action.devices.traits.TemperatureSetting'
+    ],
     'type': 'action.devices.types.THERMOSTAT',
     'willReportState': False
 }, {
diff --git a/tests/components/google_assistant/test_google_assistant.py b/tests/components/google_assistant/test_google_assistant.py
index 047fad3574c..89e9090da98 100644
--- a/tests/components/google_assistant/test_google_assistant.py
+++ b/tests/components/google_assistant/test_google_assistant.py
@@ -204,6 +204,7 @@ def test_query_climate_request(hass_fixture, assistant_client, auth_header):
     devices = body['payload']['devices']
     assert len(devices) == 3
     assert devices['climate.heatpump'] == {
+        'on': True,
         'online': True,
         'thermostatTemperatureSetpoint': 20.0,
         'thermostatTemperatureAmbient': 25.0,
@@ -260,6 +261,7 @@ def test_query_climate_request_f(hass_fixture, assistant_client, auth_header):
     devices = body['payload']['devices']
     assert len(devices) == 3
     assert devices['climate.heatpump'] == {
+        'on': True,
         'online': True,
         'thermostatTemperatureSetpoint': -6.7,
         'thermostatTemperatureAmbient': -3.9,
diff --git a/tests/components/google_assistant/test_trait.py b/tests/components/google_assistant/test_trait.py
index 42af1230eed..ef6ed7a4b8f 100644
--- a/tests/components/google_assistant/test_trait.py
+++ b/tests/components/google_assistant/test_trait.py
@@ -388,6 +388,47 @@ async def test_onoff_media_player(hass):
     }
 
 
+async def test_onoff_climate(hass):
+    """Test OnOff trait support for climate domain."""
+    assert trait.OnOffTrait.supported(climate.DOMAIN, climate.SUPPORT_ON_OFF)
+
+    trt_on = trait.OnOffTrait(hass, State('climate.bla', STATE_ON),
+                              BASIC_CONFIG)
+
+    assert trt_on.sync_attributes() == {}
+
+    assert trt_on.query_attributes() == {
+        'on': True
+    }
+
+    trt_off = trait.OnOffTrait(hass, State('climate.bla', STATE_OFF),
+                               BASIC_CONFIG)
+
+    assert trt_off.query_attributes() == {
+        'on': False
+    }
+
+    on_calls = async_mock_service(hass, climate.DOMAIN, SERVICE_TURN_ON)
+    await trt_on.execute(trait.COMMAND_ONOFF, {
+        'on': True
+    })
+    assert len(on_calls) == 1
+    assert on_calls[0].data == {
+        ATTR_ENTITY_ID: 'climate.bla',
+    }
+
+    off_calls = async_mock_service(hass, climate.DOMAIN,
+                                   SERVICE_TURN_OFF)
+
+    await trt_on.execute(trait.COMMAND_ONOFF, {
+        'on': False
+    })
+    assert len(off_calls) == 1
+    assert off_calls[0].data == {
+        ATTR_ENTITY_ID: 'climate.bla',
+    }
+
+
 async def test_dock_vacuum(hass):
     """Test dock trait support for vacuum domain."""
     assert trait.DockTrait.supported(vacuum.DOMAIN, 0)