World No.39 Thongchai defeated WBC minimumweight champion Wanheng Meenayothin to win the prestigious award for a second time after his success in 2009.
The award ceremony will be held on Monday at Indoor Stadium, Hua Mark. The other award recipients will be announced on that day.
"This is the best year of my career," said Thongchai who turned pro in 1999.
"I have played consistent golf. At one stage, I climbed to a career-high 33rd in the world."
Thongchai won his sixth European Tour title at the Nordea Masters in Sweden.
He played in all four majors and made the cut for the first time at the Masters where he finished tied for 37th.
National football coach Kiattisak Senamuang is hot favourite to win the award for the best coach in amateur sports after leading Thailand to the AFF Suzuki Cup final.
Asian Games gold medallists Wuttichai Masuk (boxing) and Chanatip Sonkham (taekwondo) are favourites to win the best amateur athlete awards in the men's and the women's categories respectively.
Meanwhile, Thongchai, 45, has been appointed ambassador of the US$2 million Thailand Golf Classic to be held at Black Mountain Golf Club in Hua Hin from Feb 12-15.
"It is a great honour to be named the tournament ambassador," said the Thai star.
"I am very proud that Thailand will be hosting the Classic which will attract some of the best golfers in the world."
The event is co-sanctioned by the European and Asian tours. Bangkok Post