SCG Muang Thong United beat 10-man Chaing Rai United 2-0 in the League Cup final at Supachalasai Stadium on Wednesday.
Goals from Peerapat Notechaiya after 35 minutes and Teerasil Dangda in the 60th minute finished off Chiang Rai.
The Beetles squandered several chances in their first ever appearance in a major cup final.
Chiang Rai's Everton Goncalves was sent off in the 88th minute for a second bookable offence.
It was a sweet revenge for the Kirins who lost to Chiang Rai in the FA Cup semi-finals.
It is Muang Thong's only silverware this season, having lost their Thai League 1 crown to bitter rivals Buriram United.
Last season, Muang Thong were declared joint League Cup winners with Buriram when the deciding match was called off after the passing of King Bhumibol Adulyadej in October last year.
Chiang Rai will have another chance to win a trophy this year when they meet Bangkok United in the FA Cup final at Supachalasai on Saturday.
Aung Thu joins Police
Myanmar international Aung Thu has joined Thai League 1 side Police Tero, according to his club Yadanarbon.
The 21-year old Myanmar international has been recognised as one of Southeast Asia's rising football talents since breaking onto the scene with the Myanmar team that qualified for the 2015 Fifa U20 World Cup, Fox Sports reported.
The mobile forward is already a regular for club side Yadanarbon and the national team, scoring eight goals in 25 appearances for his country.
His all-action displays have long seen him linked with a move overseas.
The signing comes as the Fire Dragons look to bounce back from a disappointing 2017 season that saw them finish in 14th position in the 18-team league.
They struggled for goals, scoring just 42, the joint second-worst in the division.