During his junior year, he and Kang Sang-jae, dubbed "Twin Towers" because of their height, led Korea University to a surprise win over a Sangmu team composed of experienced KBL players fulfilling their mandatory military service.

[5] Lee was considered one of the "big 3", along with Kang and Choi Jun-yong, of the 2016 KBL rookie draft and strong contenders for the first pick of the first round.

After an underwhelming start to his rookie season, he scored 24 points and 18 rebounds in January against Changwon LG Sakers.

[11][12] Lee was first called up to the senior national team while in college, participating in the 2013 FIBA Asia Championship.

The South Koreans won gold for the first time since 2002, which meant that Lee and his teammates who had yet to enlist for mandatory military service were granted exemptions.