Firefighters were called to the scene, a unit owned by ASP Supply Co Ltd, at about 12:30am.
The unit is used as a hotel materials supply depot, with the second floor used as a storeroom.
Firefighters quickly contained the fire, though the neighbouring units suffered smoke damage.
No deaths or injuries were reported from the fire.
According to police, the owner of the unit, Chirasak Thanakittham, said that fire was likely started by an electrical short circuit, though police did not explain specifically why Mr Chirasak believes so.
Lt Col Tachin Deethongon of the Chalong Police said officers were continuing their investigation and had yet to formally file their report identifying the cause of the fire.
An estimate of the damage caused by the fire has yet to be determined.