Police believe that there were no suspicious circumstances and that Mr Paine took his own life, according to reports in Thai-language media outlets.
News of his sudden death shocked former colleagues, neighbors and associates.
Mr Paine, 55, was British and had been connected with some of the Thai holiday island's best-known and finest-quality estates.
According to police, his wife said she went to bed at 9pm last night. When she awoke this morning about 7.30am, she found her husband dead in a sala by the swimming pool.
Mr Paine was a partner in the well-regarded Malaiwana development at Nai Thon beach.
He had been overseeing luxury residential real estate projects in Phuket since 2001.
Before joining Malaiwana, he successfully completed Surin Heights, the villa and condominium development above Surin Beach.
The Malaiwana estate was previously named on a list of 12 projects under investigation by authorities for encroachment on Phuket Sirinath National Park.
Mr Paine told Phuketwan in 2012 that the company named, Suree Samrit Co., Ltd, had no connection with Malaiwana.
Soon after, authorities endorsed the fact that the Malaiwana project was being developed on legal land titles.
Mr Paine's body was taken to Thalang Hospital.
People suffering from depression on Phuket are advised to talk to family and friends or consult a doctor.