Vietnam threatened Thailand's penalty area repeatedly but failed to score during main time. Their focused defense, thanks largely to amazing keeper Tran Thi Kim Thanh, also kept Thailand at bay.
The highly challenging main time ended with a nil-nil draw.
Second minute into extra time, Pham Hai Yen scored the much-awaited goal for Vietnam by heading in from a close range.
The worn-out players overcame pains and cramps to maintain the score until the last minute.
This is the sixth gold medal for Vietnam's women footballers at SEA Games and the second one in a row.