Lee trained under FNC Entertainment in 2009, and in September of that year joined CNBLUE as a bassist, replacing Kwon Kwang-jin who left the band shortly after debut.

In 2016, Lee starred alongside Jung Il-woo and Park So-dam in tvN's romantic comedy, Cinderella with Four Knights.

[13] International Network of Street Papers announced Lee's photo has been included in the Top 5 nominees for INSP Awards for Best Photograph on June 7, 2019.

The winner was announced on INSP Awards Ceremony which held as part of the Global Street Paper Summit in Hannover, Germany, on June 19.

[16] In March 2021, Lee made his acting comeback following his military discharge in the web series, Summer Guys.

The exhibition entitled, We Blew Away Dandelion Puffs, captured the moments from their visit to the fourth LOVE FNC School in Kalaw and YWAM day care center in Yangon in Myanmar last February.

[20][21] On April 7, 2019, Hope Bridge National Disaster Relief Association reported Lee donated 10 million won for the victims of forest fires in Gangwon Province.

[27] Lee was officially discharged from his military service on March 19, 2020, without returning to his base from his ETS leave according to the Ministry of National Defense’s policy.