2015–2016: Pre-debut in SM Rookies On October 13, 2015, Taeil was introduced as a member of SM Entertainment's pre-debut training team,
SM Rookies. On January 27, 2016, Taeil released "Because of You" () as a soundtrack for the TV series
The Merchant: Gaekju 2015.
2016–2021: Debut with NCT, soundtrack appearances and solo work Taeil made his official debut as a member of
NCT U, a rotational subgroup of
NCT, on April 9, 2016, with the release of the single "
Without You". Taeil later made his debut as a member of
NCT 127, the second fixed sub-unit of NCT, with the release of the EP
NCT#127 on July 7. On December 30, Taeil participated in the
SM Station charity single "Sound of Your Heart" (), a collaboration with SM artists (
Yesung,
Sunny,
Luna,
Wendy,
Seulgi and
Doyoung) and pianist
Steve Barakatt. As NCT U, Taeil,
Taeyong and Doyoung released the song "Stay in My Life" on August 7, 2017, as a soundtrack for
School 2017. Taeil, Doyoung, and
Jaehyun then released the NCT U single "Timeless" () on January 12, 2018. Taeil and Doyoung again collaborated as NCT U on "Radio Romance", a soundtrack for
Radio Romance, released on January 30, 2018. On September 7, 2018, Taeil and Jaehyun released the NCT U song "New Dream" as a soundtrack for
Dokgo Rewind. On March 30, 2019, Taeil was featured in Sohlhee's debut single "Purple" (). In November, he competed on the television show
King of Mask Singer under the nickname "King Card". The song reached number seven on the
Billboard World Digital Song Sales chart. On April 11, 2021, Taeil featured on Moon Su-jin's single "The Moon" (). On June 6, Taeil released "A Beautiful Human Being" () the second part of
Morning Dew 50th Anniversary Tribute Album, a tribute to musician
Kim Min-ki. On June 28, the fourth part of the album, featuring "Morning Dew" sung by various artists including Taeil, was released. On July 6, Taeil launched an Instagram account and broke the
Guinness World Record for "Fastest time to reach 1 million followers on Instagram", previously held by
Rupert Grint since November 2020. On October 11, Taeil, along with rapper
Lil Boi, featured on
Raiden's single "Love Right Back" from his debut EP of the same name. They performed the song together on
M Countdown and
Inkigayo that month. On December 27, SM Entertainment released the album
2021 Winter SMTOWN: SMCU Express, which includes the song "Ordinary Day", sung by Taeil and label mates
Onew and
Kyuhyun.
2022–2024: NCT Lab contributions and removal from NCT On February 13, 2022, Taeil released "Starlight" for the soundtrack of the TV series
Twenty-Five, Twenty-One. The song peaked at number 30 on the
Gaon Digital Chart, and was nominated for awards for best soundtrack at the
32nd Seoul Music Awards and at the
8th APAN Star Awards. On December 26, SM Entertainment released the album
2022 Winter SM Town: SMCU Palace, featuring the song "Happier", sung by Taeil and label mates
Kangta,
Yesung,
Suho, and Renjun. On February 9, 2023, Taeil released "Lovey Dovey" as the soundtrack of the TV series
Love to Hate You. On September 7, Taeil and
Haechan released the NCT U single "N.Y.C.T" for the
NCT Lab project. Both members participated in writing the song. Later that month, on September 22, Taeil released "Bandit" as the main soundtrack of the
Netflix series ''
Song of the Bandits. On August 28, 2024, SM Entertainment announced Taeil's removal from NCT following sexual offense allegations. On October 16, SM Entertainment announced the termination of Taeil's contract through a mutual agreement. ==Personal life and rape conviction==