Born in Seoul, South Korea and raised in Troy, Michigan, Yeun began his foray into acting while studying Psychology at Kalamazoo College in Kalamazoo, MI. After seeing a performance of the school's improv group, he decided to switch his focus to acting. Following graduation, Yeun moved to Chicago, where he performed with the famed Second City Theatre comedy troupe in various shows with their Touring Company. He has been a part of several improvisational / sketch comedy groups including Stir Friday Night, Hands, and Detective Detective.