Following her appearance on the SBS audition program K-pop Star 2 alongside her brother Lee Chan-hyuk, she debuted as the vocalist of the sibling duo AKMU on April 7, 2014, under YG Entertainment after winning the show.

She has also sung original soundtracks for Korean television dramas including It's Okay to Not Be Okay, and the Disney live-action film Mulan.

Additionally, while watching SBS variety program Star King, she found the voice of a girl named Shannon intriguingly beautiful, also triggering her to pursue music.

After residing in Mongolia for almost five years, Lee temporarily moved back to South Korea due to an issue with her visa.

[3] In August 2012, she and her brother auditioned for SBS' K-pop Star 2 as AKMU, soon finishing in first place and later signing under YG Entertainment.

[12] On May 25, 2017, Lee created the beauty YouTube channel, MochiPeach, and publicly uploaded her first-ever video on June 3.

[16] Through the Netflix television series Temporary Idol, Lee made her acting debut by joining the main cast as a character depicting herself.

[22] Through the tvN historical melodrama Mr. Sunshine, Lee became the fourth artist to release a soundtrack for the television drama on July 29, 2018.

"[27] On April 27, 2019, Lee was invited to participate in the first anniversary of the Panmunjom Declaration event, where peace and reunification of the Korean Peninsula was adopted between the Supreme Leader of North Korea, Kim Jong Un, and the President of South Korea, Moon Jae-in, during the April 2018 inter-Korean summit.

[28] In September 2019, through AKMU's third studio album Sailing, Lee was credited as the arranger for the B-side track "Farewell" (작별 인사), marking her first-ever participation among their releases.

The occasion was hosted by the actor, Kim Dong-wook and announcer Lee Jung-min as well as attended by the South Korea president, Moon Jae-in.

Upon release, the original soundtrack, "In Your Time" (아직 너의 시간에 살아), spawned to number one on South Korean music streaming platforms including Genie and Bugs on July 14.

[35] The music video released through the platforms, YouTube and Naver TV received attention garnering over 1 million views domestically within 2 days, and peaked at number 3 on the Naver TV top 100 popular videos chart while remaining within the top 10 for one week upon release.

[38] Soon, YG Entertainment announced Lee would officially debut as a solo artist on October 16 with the digital single "Alien".

[40] Following the COVID-19 pandemic, Lee made a donation of 50 million won on April 1, 2020, to the Daegu Dongsan Hospital medical staff.