The Thais lost to Singapore in the previous final as the Lions claimed a record fourth crown.
In Hanoi, hosts Vietnam beat the Philippines 3-1 and Indonesia hammered Laos 5-1 in the last Group A matches yesterday.
Group A winners Vietnam and runners-up the Philippines advanced to the semi-finals.
The semi-finals will be played over two legs on Dec 6-7 and Dec 10-11. The two-legged final is scheduled for Dec 17 and 20.
The biennial tournament began in 1996.