The two teams entered the best-of-three decider on Wednesday after being locked 1-1.
Ban Bueng Devil Rays received 700,000 baht as prize money.
The team also earned a slot in the 2022 FIBA Asia Champions Cup at the end of this year.
Taishaun Johnson from the champion team was declared Most Valuable Player.
Runners-up Thung Khru Hi-Tech received prize money of 600,000 baht. Bangkok Tigers Sniper, who finished third, received 500,000 baht while fourth-place Nonthaburi TGE got 400,000 baht.
The 2022 Thailand Basketball League, organised by the Thai Basketball Professional Association, began on June 25. Ten teams were in the fray for a total prize money of 4 million baht.