No people were injured in the incident.
The bus, registered in Phuket and operated by Piyachoke Sakorn Co Ltd, came to a halt near the Kathu Shooting Range at the bottom of the steep descent on the Kathu side of the hill.
Lt Amphon Wattanangruang of the Kathu Police reported that the bus was carrying 23 Vietnamese tourists from a hotel in the Patong area to go to the airport.
The driver of the bus was taken to Kathu Police Station for further questioning while offials arranged for the bus to be safely recovered from the scene.