He rendered the mandatory military service at 19 years old. Park Seo Joon performed his military duties from 2008 to 2010. In his Esquire interview, he also shares that he read a lot of self-help books while in the military. A year after getting discharged, he made his entertainment debut by appearing in Bang Yong Guk’s music video “I Remember”.

He was discharged from the army in 2010. For the actor, fulfilling the military service was his first priority. Joon was assigned to the Security Guard Battalion and finished his service at the Cheongju Correctional Facility. He’s one of the very few actors who didn’t have to put his acting career on hold for military duties.