In 2016, Kyulkyung participated in Mnet's survival television show, Produce 101, along with other five trainees from her agency, Pledis Entertainment. She and Nayoung were the only one to made it to the final line up, ranking 6th and 10th respectively, becoming members of the girl group I.O.I.
On May 4, 2016, she debuted in I.O.I with the mini album, Chrysalis, and its title track, "Dream Girls".
2017–2020: PRISTIN, legal dispute with Pledis
After the disbandment of I.O.I on January 29, 2017, Pledis announced that Kyulkyung and Nayoung would debut together with their former Produce 101 contestants, as members of PRISTIN, which debuted on March 21, 2017 with the mini album Hi! PRISTIN and its title track, "Wee Woo".
In 2018, the agency formed PRISTIN's first sub-unit, PRISTIN V, with Kyulkyung being one of its members. They debuted on May 28 with the single album, "Like a V".
On September 6, 2018, she made her Chinese solo debut with the digital single "Why", which was promoted exclusively in China.
On May 24, 2019, it was announced by Pledis that PRISTIN was officially disbanding after almost two years without activity. She, along with Sungyeon and Yehana, would be staying with the agency, with the remaining 7 members departing.
On September 2019, Kyulkyung sent a contract termination notice to Pledis and XCSS Entertainment, her Chinese agency, which led them to demand her for breaching the contract on March 25, 2020, declaring the notice as "baseless". The same day Kyulkyung had released a statement on her Weibo.