The accident occurred just after 11am, the Patong Municipality Fire Department told The Phuket News.
The driver, Surachai Choosin, escaped serious injuries.
No other vehicles were involved in the accident, which Mr Surachai attributed to brake failure while descending the steep hill into Patong.
Traffic heading into Patong on the busy road has been affected.
Officers from the Patong branch of the Department of Disaster Prevention and Mitigation (DDPM Patong) are on the scene and cleaning up the oil spilled onto the road by the overturned truck.
Lt Col Chompunoot Anantakul of the Patong Police told The Phuket News that he had yet to question Mr Surachai further and have the truck inspected before he could determine whether any charges were to be pressed for the accident.
Mr Surachai was not tested for alcohol or other substances, but does hold the correct driver’s licence for operating the truck, Lt Col Chompunoot added.