ONE debuted with the hip-hop duo 1Punch in 2015 with Samuel. They released the single album The Anthem featuring the lead single Turn Me Back. That same year, he appeared in the fourth season of Mnet’s Show Me the Money, but was eliminated. He returned in the show’s fifth season, where he placed tenth overall. In 2017, ONE launched a solo career with the release of the single album One Day, which peaked at number 6 on the Gaon Album Chart. He then made his acting debut with a supporting role in the 2017 tvN series Hwayugi. In 2018, he appeared in the tvN revenge thriller Room No. 9. In 2019, he became part of the tvN romantic comedy Her Private Life. He later landed his first big screen role as a terminally ill high school student in Goodbye Summer. Later in 2019, he dropped his first studio album titled PRVT01.