He first gained recognition for starring in the film Set Me Free (2014) and the television series Hogu’s Love (2015) before coming to international prominence for his roles in the films Train to Busan (2016) and Parasite (2019) both of which were critical and commercial successes with the latter winning the Palme d'Or at Cannes and the Academy Award for Best Picture.

[5] Supporting roles followed, and Choi was cast in crime drama Special Affairs Team TEN as detective Park Min-ho.

[7] He made his big screen debut that same year, starring as a supporting character in the film Flu and Secretly, Greatly.

In the interim, Choi played several characters on television series such as Rooftop Prince, You Are My Destiny and Pride and Prejudice.

[10][11] Later that year, Choi also starred in the action comedy film Big Match, playing the role of genius hacker Guru.

[13] Choi first gained international recognition with the blockbuster zombie thriller film Train to Busan, where he played the role of high school baseball player, Yong-guk.

[15] This marked his first collaboration with director Bong Joon-ho and featured an international cast, including Tilda Swinton and Paul Dano.

In a press interview, co-star Park Hee-soon remarked that Nobleman could be Choi's once-in-a-lifetime character.

Choi was first approached by Bong after their first collaboration with Okja in 2016, who told the actor to "stay skinny" to play the character.