Best known for his role as Paul in the ABC Family original series The Nine Lives of Chloe King, he landed the part of Minho in the Maze Runner films. In 2015, he began playing Dong on the Netflix series Unbreakable Kimmy Schmidt.
He had a starring role in the short-lived series MotherLover as Chaz Seong.
He moved from South Korea to New Zealand at the age of 7 where he learned English. He later moved to Southern California. In 2015, he married Hayoung Choi.