Lt Col Narong Muangduang of Wichit Police was notified at 5pm that found a body had been seen floating off a beach at Koh Tapao Noi.
Wichit Police Chief Col Nikorn Somsuk and fellow officers responded by dispatching officers in a dinghy to recover the body.
Due to the state of the body, dressed in a black long-sleeved shirt but no trousers, police believed the man died at least three days earlier.
Kusoldharm Foundation rescue workers brought the body back to Saphan Hin, from where it was taken to Vachira Phuket Hospital to be examined by the doctors there.
During the initial investigation by Wichit Police, officers from Phuket Marine Police confirmed that they were informed on Friday that a man had fallen overboard from a fishing boat in the area.
The fishing boat operated out of Rassada Pier, officer said.
A search failed to find and safely recover the man, police were told.
Wichit Police reported that they suspect that the body found yesterday is of the missing man, and that they are contacting relatives to confirm whether or not it is.
Officers are also waiting for doctors at Vachira Hospital to conclude their post-mortem examination to determine whether any foul play was involved.