diff --git a/homeassistant/components/thermostat/honeywell.py b/homeassistant/components/thermostat/honeywell.py
index f45b07b9fd6..b31dfea0b4b 100644
--- a/homeassistant/components/thermostat/honeywell.py
+++ b/homeassistant/components/thermostat/honeywell.py
@@ -136,11 +136,20 @@ class RoundThermostat(ThermostatDevice):
         """Set new target temperature."""
         self.device.set_temperature(self._name, temperature)
 
+    @property
+    def operation(self: ThermostatDevice) -> str:
+        """Get the current operation of the system."""
+        return self.device.system_mode
+
     @property
     def is_away_mode_on(self):
         """Return true if away mode is on."""
         return self._away
 
+    def set_hvac_mode(self: ThermostatDevice, hvac_mode: str) -> None:
+        """Set the HVAC mode for the thermostat."""
+        self.device.system_mode = hvac_mode
+
     def turn_away_mode_on(self):
         """Turn away on.
 
@@ -219,6 +228,11 @@ class HoneywellUSThermostat(ThermostatDevice):
         else:
             return self._device.setpoint_heat
 
+    @property
+    def operation(self: ThermostatDevice) -> str:
+        """Return current operation ie. heat, cool, idle."""
+        return self._device.system_mode
+
     def set_temperature(self, temperature):
         """Set target temperature."""
         import somecomfort
@@ -244,3 +258,7 @@ class HoneywellUSThermostat(ThermostatDevice):
     def turn_away_mode_off(self):
         """Turn away off."""
         pass
+
+    def set_hvac_mode(self: ThermostatDevice, hvac_mode: str) -> None:
+        """Set the system mode (Cool, Heat, etc)."""
+        self._device.system_mode = hvac_mode
diff --git a/tests/components/thermostat/test_honeywell.py b/tests/components/thermostat/test_honeywell.py
index 7a5b4c93a98..e4f75e508e5 100644
--- a/tests/components/thermostat/test_honeywell.py
+++ b/tests/components/thermostat/test_honeywell.py
@@ -277,6 +277,16 @@ class TestHoneywellRound(unittest.TestCase):
         self.round1.set_temperature(25)
         self.device.set_temperature.assert_called_once_with('House', 25)
 
+    def test_set_hvac_mode(self: unittest.TestCase) -> None:
+        """Test setting the system operation."""
+        self.round1.set_hvac_mode('cool')
+        self.assertEqual('cool', self.round1.operation)
+        self.assertEqual('cool', self.device.system_mode)
+
+        self.round1.set_hvac_mode('heat')
+        self.assertEqual('heat', self.round1.operation)
+        self.assertEqual('heat', self.device.system_mode)
+
 
 class TestHoneywellUS(unittest.TestCase):
     """A test class for Honeywell US thermostats."""
@@ -327,6 +337,16 @@ class TestHoneywellUS(unittest.TestCase):
         self.assertEqual(74, self.device.setpoint_cool)
         self.assertEqual(74, self.honeywell.target_temperature)
 
+    def test_set_hvac_mode(self: unittest.TestCase) -> None:
+        """Test setting the HVAC mode."""
+        self.honeywell.set_hvac_mode('cool')
+        self.assertEqual('cool', self.honeywell.operation)
+        self.assertEqual('cool', self.device.system_mode)
+
+        self.honeywell.set_hvac_mode('heat')
+        self.assertEqual('heat', self.honeywell.operation)
+        self.assertEqual('heat', self.device.system_mode)
+
     def test_set_temp_fail(self):
         """Test if setting the temperature fails."""
         self.device.setpoint_heat = mock.MagicMock(