Kunlavut Vitidsarn made history on Sunday when be became the first player to win three successive boys' singles title at the BWF World Junior Championships.
The top seeded Thai defeated 10th seed Christo Popov of France 21-8, 21-11 in the boys' singles decider in Kazan, Russia.
Kunlavut was the second player to achieve the historic treble. Fellow Thai Ratchanok Intanon was the first player to win three straight junior world crowns when she won the girls' singles titles from 2009-2011.
The 18-year-old Kunlavut, the top-ranked junior player in the world, proved too fast and too strong for the left-handed Popov, winning the championship match in just 36 minutes.
Indonesia's Yonathan Ramlie, who lost to Kunlavut in the semis, and China's Li Yunze, who was beaten by Popov, took the bronze medals.
Apart from Kunlavut's historic success in Kazan on Sunday, the Thai shuttlers also won two bronze medals in the girls' singles and the mixed doubles categories.
In the girls' singles event, top seed Phittayaporn Chaiwan had to settle for a bronze medal after losing to seventh seed Riko Gunji of Japan in the semi-finals on Saturday.
Gunji on Sunday upset second seed Zhou Meng of China 21-13, 12-21, 21-14 in a thrilling final.
In the mixed doubles event, third seeds Ratchapol Makkasasithorn and Benyapa Aimsaard lost to eventual winners Feng Yanzhe and Lin Fangling of China, the No.2 seeds, on Saturday.
Feng and Lin defeated top seeds and defending champions Leo Rolly Carnando and Indah Cahya Sari Jamil of Indonesia 21-17, 21-17 in the title match on Sunday.
Thailand won the bronze medal at the BWF World Mixed Team Junior Championships in Kazan earlier this month.
The team lost to favourites Indonesia 3-2 in the semi-finals. The Indonesians went on to defeat China 3-1 in the title decider.