Kim attended Duk-soo High School and graduated from Daekyung University on February 15, 2013, majoring in practical music.

[5] In 2011, he made his acting debut in Japanese drama Jiu Keishicho Tokushuhan Sousagakari, which aired on TV Asahi in July.

[6] In 2012, he was cast in tvN's romance comedy series Flower Band, as a guitarist of a rock group.

[9] In August 2013, he had a cameo in SBS's Master's Sun, playing the younger version of So Ji-sub's character.

[10] In 2014, he was cast in supporting roles in MBC's Cunning Single Lady and SBS's My Lovely Girl.

[17] His portrayal of a commoner who stands in for the king earned viewers' approval, and he was named Actor of the Month in June by MBC Dramanet.

[31] On November 12, 2024, L has signed a contract with Universal Records Philippines and GLXY Talent Management.

[34] On February 22, 2021, L enlisted for his mandatory military service as a member of the Republic of Korea Marine Corps.