Housekeeping staff discovered the body on Wednesday and notified local authorities, according to The Guardian.
Police found the man lying on the bed with his phone resting on his chest. He had bandaged injuries on his elbow and wrist, reportedly from a recent road accident.
Officers found no signs of assault or theft in the room, News.com.au reported. There were no illegal drugs or alcohol present, only a few over-the-counter pills that had reportedly been given to him by a hotel employee.
Thai authorities have informed the Australian Embassy in Bangkok of the death.
The man's body has been transferred to Vachira Phuket Hospital for a post-mortem examination to determine the exact cause of death.
The case is the latest in a series of recent incidents involving Australian tourists in Thailand.
Earlier this month, a 43-year-old Australian man was found dead at a massage parlor on Koh Samui island after staff heard him snoring and later realized he was unresponsive.
Just days later, another Australian man was found dead in an apartment in Pattaya.