Beginning In 1992, Seo briefly worked in the sales department of Hyundai Motor Company before joining the Theatre Company Michu. During his five-year tenure with the company, he gained experience in translation, creative writing, and performance. His credits with the troupe include ''General Oh's Claw
by Park Jo-yeol, Namsadang Sky'', and several MBC Madangnori productions. The production featured a contemporary reimagining of the classic play; Seo's Hamlet was depicted wearing modern clothing and carrying a pistol, while Claudius was portrayed as a democratic leader. For his performance, Seo received the Best Actor award at the 2008 Korea Drama Awards and a 2008 Commendation from the Minister of Culture, Sports and Tourism. In 2008, the NTCK and director Jens-Daniel Herzog collaborated again for a second run of
Terrorist Hamlet, staged as the 210th "World Masterpiece Stage" regular performance. Seo reprised his role as Hamlet.
Career as freelance actor In 2011, Seo performed alongside Kim Young-pil, Kim Joo-wan, and
Jeon Mi-do in the play
The Author by British playwright
Tim Crouch. Directed by Kim Dong-hyeon, the production served as the inaugural entry in the Doosan Art Center's "Borderline" series. The play is characterized by its experimental structure, which blurs the distinction between the performers and the audience while examining the psychological impact of violent theatrical content on both creators and viewers. Seo made his television debut in 2017 with a minor role as a pastor in the series
Prison Playbook. Following this debut, he continued to take primarily minor and supporting roles in television and film while maintaining his focus on theater. In 2019, he made a cameo appearance in the independent film
Lucky Chan-sil. == Filmography ==