The body was sighted at about 8.30am on Saturday morning and retrieved shortly after 10am. The body has been taken to shore for autopsy and identification.
If confirmed, this will be the eighth victim from the warship’s sinking, with 21 Royal Thai Navy sailors still missing.
The Rattanakosin-class corvette, with 105 people on board, capsized on Sunday night some 20 nautical miles (32 kilometres) off the coast of Prachuap Khiri Khan’s Bang Saphan district. It was patrolling the area in rough weather.
Rescuers believe there could be more bodies trapped in the warship’s wreckage.
Of the 76 crew who have been rescued, 19 are in hospitals while 57 have been allowed to go home.
The Navy has deployed an underwater SeaFox drone to examine the wreck with cameras ahead of a possible salvage mission.