Dang, seed No 13, defeated No 1 Sathish Kumar Karunakaran of India 21-17, 21-18 in the men's singles final in 50 minutes.
Earlier, Dang became the 'giant killer' as he ousted No 11 Meiraba Maisnam from India (21-17, 17-21, 21-16) in the quarter-finals and No 8 Viren Nettasinghe from Sri Lanka (21-15, 21-19) in the semi-finals.
The world No 97 Dang is the first Vietnamese athlete taking a top podium this year.
Dang, one of two male badminton players of Vietnam trying to secure their Olympic spot, had never won internationally before. His best result was a second-place finish at the 2022 Croatia Open. In 2023, he won bronze medals at the Hangzhou China International Challenge in China and Sydney International Challenge in Australia.
He received 4,000 points to upgrade his world position and may enter the Road to Paris ranking's top 35 when the new list is announced on February 7.
Dang currently has 20,870 points, while the No 34 in the list, Dmitriy Panarin of Kazakhstan, has 20,310 points.
The best 35 players and three wildcard holders will be selected to compete in Paris in July.
Dang will next take part in the Azerbaijan International Challenge from February 5-12.
