2016–2022: Debut with Loona and Mix Nine On September 26, 2016,
Blockberry Creative announced that Heejin was going to be the first member of their upcoming girl group
Loona. As part of the group's pre-debut release strategy, Heejin then went on to release her
self-titled single album alongside its single "Vivid" on October 5. In November 2016, Heejin was featured on the song "I'll Be There" on the
debut single album of Loona member
HyunJin. The two also later featured on the song "The Carol", which was released as part of Loona member
Haseul's
debut single album in December, 2016. In January 2017, Heejin would collaborate once again with Hyunjin for the song "My Sunday" which was released as part of Loona member
Yeojin's debut solo album. On February 14, 2017, Heejin was announced to debut in Loona's first sub-unit
Loona 1/3 alongside members Haseul, Hyunjin, and Vivi. They subsequently debuted on March 13 with their mini album
Love & Live. In October, Heejin auditioned alongside members Haseul, and Hyunjin for the survival reality show
Mix Nine. She passed the audition, and went on as a participant until the final episode, where she finished 4th amongst the female participants. On March 30, 2018, Heejin featured on the song "Rosy" alongside her members Gowon and
Hyeju (also known by her former stage name Olivia Hye), which was part of Olivia Hye's
debut single album. Heejin officially debuted with Loona as a full group on August 20, 2018 with the release of their debut EP + + (EP)|
[+ +]. On November 28, 2022,
JTBC Entertainment News reported that nine members of Loona, including Heejin, had filed an application for a provisional injunction to suspend their exclusive contract with Blockberry Creative, following member
Chuu's expulsion three days earlier.
2023–present: Solo activities and re-debut with Artms On January 13, 2023, it was reported that Heejin, alongside
Odd Eye Circle members Kim Lip,
Jinsoul, and
Choerry, had been granted a preliminary injunction against her contract with Blockberry Creative. On March 17, Heejin signed an exclusive contract with Modhaus, an agency founded by Loona's former creative director Jaden Jeong On April 1, Heejin was announced as a member of
Artms along with other Loona members Kim Lip, Jinsoul, and Choerry. She made her solo debut with the extended play
K on October 31. The English and rock versions of the lead single "Algorithm" were released on September 23, 2024. On November 13, 2025, Heejin released the digital single "Savior" (stylized as "sAvioR"), a rock song, accompanied by a music video. ==Discography==