After nine matches, Liem, with an Elo rating of 2,713, was tied for first with 7.5 points alongside American Jeffery Xiong (Elo 2,691).
Liem and Xiong entered a blitz match to decide the winner, in which Liem forced his opponent to a draw after 36 moves. Liem received bonus points for playing black and was declared champion.
He walked away with US$15,000 for the title and a bonus of US$500 for winning the tiebreak.
This is the first World Open title for Liem and his third consecutive crown within a month, following his two victories at the 2019 Summer Chess Classic and the 2019 Asian Continental Championships.
Following the championship, Liem has an Elo rating of 2,725.5, advancing two places to the 29th position in the world ranking.