Lt Sanya Suksawat of the Phuket City Police was called to the scene, in Soi Bang Chee Lao 2 in Moo 2, Rassada, at 9:30am.
Police together with firefighters from Rassada Municipality Fire Department arrived to find the speedboat and the ground around it ablaze.
Firefighters took about 15 minutes to put the fire out, but by that time the speedboat had been destroyed.
Saman Upama, 65, who lives in the house where the boat was parked, told police that he was inside the home when smoke started coming into the house.
Mr Saman ran out to see a pile of garbage nearby on fire. He called the fire department and tried to douse the fire by himself, but was unsuccessful, Lt Sanya reported.
While Saman was battling the flames, the fire spread to the boat, and consumed it.
Lt Sanya said police were continuing their investigation into how the fire started.
No people were injured from the fire, but the damage caused to the boat was estimated to be about B400,000 to B500,000, Lt Sanya noted.