After completing his military service with Sangju Sangmu FC in October 2015, Lee returned to his original club, Busan, but only appeared in three matches due to injury.

[5] Lee returned to Busan ahead of the 2019 season and scored two goals in a 5-2 victory against Asan Mugunghwa FC on April 13.

[7] In December 2014, Lee was surprisingly included in South Korea's squad for the 2015 AFC Asian Cup as an uncapped player.

[8] 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.

[10][11] 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.