Choi has appeared films such as Superstar Thank You and The Terror Live, as well as in various television dramas, including Bridal Mask, Big, Crazy Love, The Queen of Office, Six Flying Dragons, My Father Is Strange, Lawless Lawyer, Heart Surgeons, and Confession.
He then gained more popularity for his breakthrough role as a Sungkyunkwan Confucian student Jo Mal-saeng in the SBS historical drama Six Flying Dragons.
[6] In 2017, Choi left a strong impression on TV viewers in the role of the righteous elite prosecutor Kim Yoon-soo in the SBS drama Oh, the Mysterious.
Two days later, on May 12, he made his appearance in first episode of tvN drama Lawless Lawyer as Seok Gwan-dong, the leader of the East Crown gang in Seoul.
Choi's portrayal was highlighted for his witty dialogue, refreshing expressions, and endearing silliness, which made the character a standout.
Viewers commended Choi's performance as funny, cute, and cunning, bringing a cheerful and playful energy to the story.
[10] Also in July, Choi return to the stage with John Steinbeck's play Of Mice and Men with role Lenny.
[12] In September, he reprise his role Lenny in John Steinbeck's play Of Mice and Men and received a standing ovation for his performance.
[14] In 2020, Choi proved his acting prowess with the cool, level-headed team leader Lee Woo-cheol in the tvN drama Flower of Evil.
[18] In 2022, he appeared in many roles, Jang Seung-jun from Extraordinary Attorney Woo, Chun Sang-woo from Model Detective 2, Noh Seung-hwan from Insider, and the sleep clinic doctor from Decision to Leave.
Despite his simple nature, viewers initially suspected Seo of being a "villain" character due to his behavior toward his former colleague, Cheon Ji-hoon.