In December 2014, Lee was surprisingly included in South Korea's squad for the 2015 AFC Asian Cup as an uncapped player. He made his debut for the "Taegeuk Warriors" in a pre-tournament friendly against Saudi Arabia, scoring his first international goal as the Koreans ran out 2–0 winners. In South Korea's final group game, Lee scored the winning goal against tournament hosts Australia to secure first place in Group A. On 26 January 2015, Lee scored the opening goal of South Korea's 2–0 semi-final defeat of Iraq to put the nation into the Asian Cup final for the first time since 1988.