The organisers of the competition said Thanh Vy’s confidence and beauty shone out above her rivals, securing her victory and a place in the top three.
Vietnam sent two representatives to the pageant: Pham Huong, F-Idol 2011 winner, and Dong Thanh Vy, an accounting student.
Last year, Vietnamese beauty Dieu Han was crowned at the contest.
Miss ASEAN 2013 was a girl named Amande Leong Li Ting from Singapore, and the first runner up was Amelia Thripura Henderson from Malaysia.
The glitzy final was recorded on Fashion TV and is expected to be broadcast later this year.