The War Elephants made up for their loss against arch-rivals Malaysia with an upset win over a Caribbean side who lie 10 places above them in the FIFA world rankings.
Midfielder Channarong Promsrikaew bagged his first goal for Thailand in the 21st minute, slotting home after Trinidad and Tobago keeper Marvin Phillip deflected a shot into his path. But Kareem Moses levelled from a corner in the 61st minute, his header deflecting into the net off defender Kritsada Kaman.
As home fans at the 700th Anniversary Stadium grew anxious at the prospect of a second successive defeat, Supachok Sarachat found himself in space on the edge of the Trinidad and Tobago area. Wrapping his foot around the ball, he sent it curling just inside the post to grab the decisive goal.
He also secured the bonus of 2 million baht that manager Nualphan Lamsam had promised to pay the players if they won. Nualphan wants Thailand to improve their FIFA world ranking of 111th.
Meanwhile, Tajikistan were crowned King's Cup champions after beating Malaysia 3-0 in a penalty shootout on Sunday night.