The 64-year-old Swede will supervise training sessions and work on the strategy of the Bangkok-based club, Belgian coach Robert Procureur told a press conference.
The salary was not disclosed. His initial contract runs until the end of the current season finishing next month.
Eriksson, England's first foreign head coach from 2001 to 2006, said he hoped to help raise Thai football standards.
"I don't know what other people think but I decide to take this job. If I can help it will be good," he said.
"It is my first time in Asia and I am very excited to see the games."
Since leaving the England job, Eriksson has had unsuccessful spells at Manchester City and Mexico, among others.