diff --git a/homeassistant/components/tasmota/fan.py b/homeassistant/components/tasmota/fan.py
index 362149e9fca..bdcc00dc764 100644
--- a/homeassistant/components/tasmota/fan.py
+++ b/homeassistant/components/tasmota/fan.py
@@ -63,7 +63,7 @@ class TasmotaFan(
     @property
     def speed_list(self):
         """Get the list of available speeds."""
-        return list(HA_TO_TASMOTA_SPEED_MAP.keys())
+        return list(HA_TO_TASMOTA_SPEED_MAP)
 
     @property
     def supported_features(self):
@@ -72,6 +72,8 @@ class TasmotaFan(
 
     async def async_set_speed(self, speed):
         """Set the speed of the fan."""
+        if speed not in HA_TO_TASMOTA_SPEED_MAP:
+            raise ValueError(f"Unsupported speed {speed}")
         if speed == fan.SPEED_OFF:
             await self.async_turn_off()
         else:
diff --git a/tests/components/tasmota/test_fan.py b/tests/components/tasmota/test_fan.py
index 5cadc20218e..1aca8c84e07 100644
--- a/tests/components/tasmota/test_fan.py
+++ b/tests/components/tasmota/test_fan.py
@@ -7,6 +7,7 @@ from hatasmota.utils import (
     get_topic_tele_state,
     get_topic_tele_will,
 )
+import pytest
 
 from homeassistant.components import fan
 from homeassistant.components.tasmota.const import DEFAULT_PREFIX
@@ -152,6 +153,33 @@ async def test_sending_mqtt_commands(hass, mqtt_mock, setup_tasmota):
     )
 
 
+async def test_invalid_fan_speed(hass, mqtt_mock, setup_tasmota):
+    """Test the sending MQTT commands."""
+    config = copy.deepcopy(DEFAULT_CONFIG)
+    config["if"] = 1
+    mac = config["mac"]
+
+    async_fire_mqtt_message(
+        hass,
+        f"{DEFAULT_PREFIX}/{mac}/config",
+        json.dumps(config),
+    )
+    await hass.async_block_till_done()
+
+    async_fire_mqtt_message(hass, "tasmota_49A3BC/tele/LWT", "Online")
+    state = hass.states.get("fan.tasmota")
+    assert state.state == STATE_OFF
+    await hass.async_block_till_done()
+    await hass.async_block_till_done()
+    mqtt_mock.async_publish.reset_mock()
+
+    # Set an unsupported speed and verify MQTT message is not sent
+    with pytest.raises(ValueError) as excinfo:
+        await common.async_set_speed(hass, "fan.tasmota", "no_such_speed")
+    assert "Unsupported speed no_such_speed" in str(excinfo.value)
+    mqtt_mock.async_publish.assert_not_called()
+
+
 async def test_availability_when_connection_lost(
     hass, mqtt_client_mock, mqtt_mock, setup_tasmota
 ):