Rawai Deputy Mayor San Chang Lek and municipal disaster prevention officers were called to the beach by lifeguards after being alerted by local residents.
The turtle, estimated to weigh about 20kg, was found in good condition with no immediate signs of injury or decay.
Municipal officers contacted the Center for Marine and Coastal Resources Research, operated by the Department of Marine and Coastal Resources (DMCR), to examine the carcass and determine the cause of death.
Officials reminded beachgoers to report any sightings of stranded or injured marine animals so that specialists can respond promptly.