Lee enlisted for his mandatory military service on 15 June 2010 at the 102 Reserves in Chuncheon, Gangwon Province for four weeks of basic training followed by 21 months of active duty. He served at the Defense Media Agency of the Ministry of National Defense and was appointed Honorary Ambassador of Military. He was discharged on 28 March 2012, and on the same day, he was appointed promotional ambassador for the 2012 Korean Formula One Grand Prix held at the Korea International Circuit in October.