The Bac Giang-born runner finished first in the women’s 5,000m race with a time of 16:45.98.
This is the second gold medal of Oanh and the 11th of Vietnamese track and field athletes at SEA Games 30.
Oanh’s teammate Pham Thi Hue won the silver medal in the women’s 5,000m race.
Also on December 10, Oanh will compete in the women’s 3,000m hurdle category.
Meanwhile, runner Bui Van Su bagged another silver medal for Vietnam in the men’s 110m hurdle race with a time of 15.08 seconds.