The Thai top seed and world No.2 battled past second seed Anders Antonsen of Denmark in three games, 21-16, 17-21, 21-9 in the World Tour Super 500 final at Nimibutr Stadium.
It was his second Thailand Open triumph since his maiden victory in 2023, reports the Bangkok Post.
Kunlavut, whose nickname is View, won the Asian Championships last month.
Earlier, compatriot Pornpawee Chochuwong was unable to make it two out of two for Thailand.
The top seed lost to second seed Chen Yufei 16-21, 12-21 in the women’s singles decider.
Chen headed into yesterday’s title match with a massive advantage in the pair’s head-to-head record, holding a 13-1 lead.
The Chinese continued her dominance against Pornpawee as she claimed her second Thailand Open title and her third win this year with a dominant victory in 48 minutes.
Chen won her first Thailand Open in 2019. It was one of the first she won in her senior career and “an important title in my career,” she said prior to yesterday’s final.
Former Olympic champion Chen took a break following her early exit from the Paris 2024 Games, where she fell in the quarter-finals to her now-retired compatriot He Bingjiao.
Her return to competition began with the Badminton Asia Mixed Team Championships in February. After steady performances at the Orleans Masters and the All England Open, she hit her stride by clinching back-to-back titles at the Swiss Open and Badminton Asia Championships.
Meanwhile top seeds Pearly Tan and Thinaah Muralitharan were crowned champions in the women’s doubles event.
The Malaysian pair defeated Jeong Na-Eun and Lee Yeon-Woo of South Korea 21-16, 21-17 to claim the top honours.
Second seeds Aaron Chia and Soh Wooi Yik made it two for Malaysia after they took home the men’s doubles crown.
They beat unseeded William Kryger Boe and Christian Faust Kjaer of Denmark 20-22, 21-17, 21-12.
In the mixed doubles final, second seeds Feng Yanzhe and Huang Dongping earned the second title for the Chinese contingent after they defeated compatriots Guao Jiaxuan beat Wu Mengying 24-22, 21-16.