 On November 3, 2017, Aung La Nsang faced Alain Ngalani at in the first openweight bout in ONE Championship history, winning by submission.Later that year he met with State Counsellor of Myanmar Aung San Suu Kyi to discuss the issues in the Kachin State.On February 23, 2018, he stopped Alexandre Machado at in Yangon to win the ONE Light Heavyweight World Championship to become only the second fighter, after Martin Nguyen, to win ONE Championship titles in two divisions.