The Vietnamese boxer took the title on a split decision with two judges scoring Nhi at 96 points, two more than her Japanese rival Etsuko Tada after 10 rounds of the women's mini-flyweight title fight.
Nhi made history becoming the first ever Vietnamese to win a professional WBO belt.
Nhi was considered the underdog compared to her 40-year-old opponent in both experience and record./.
VNA