Phayahong was declared the winner after beating the reigning Krush Atomweight champion Sukawara Miyu of Japan at Yoyogi National Gymnasium in Shibuya.
The fight was ruled a majority decision draw after the first three rounds, with one judge scoring the bout for Phayahong. She was awarded the split decision after an extra fourth round was fought.
K-1 is a Professional Kickboxing promotion established in 1993. The only previous Thai title winners were all men - Buakaw Banchamek, Kaew Viriyalekgym and Kongnapa Viriyalekgym.
Buri Ram native Phayahong, real name Chanthakan Manobal, is a cousin of Lalisa Manobal, better known as Lisa Blackpink, a Thai rapper, singer and dancer based in South Korea who is a member of the South Korean girl group Blackpink.
Phayahong is a former student of Nakhon Ratchasima Sports School and began boxing at the age of nine, wininng her first title at the age of 13. She is currently a student in the faculty of education at Kasetsart University.
She won a bronze medal in the 48kg weight at the recent SEA Games in Hanoi. She was also named an outstanding performer of the boxing coach reverence dance, or wai khru, on National Muay Thai Day, Feb 6, in 2020.