In December 2016, he starred in two episodes of the special web drama "First Seven Kisses" which was produced by Lotte Duty Free. In January 2017, Kai was announced to be starring as the male lead in the KBS teen drama "Andante", playing a high school student. In February 2017, he was cast in the Japanese drama "Spring Has Come", based on the Japanese novel of the same name. The drama marks the first time a non-Japanese actor taking a lead role on a drama produced by the broadcasting station WOWOW. In December 2017, Kai was chosen as the cover model for December's issue of The Big Issue, which is a magazine known for helping the homeless. The magazine sold out 20,000 copies within the first two days, and until now, 80,000 copies have been sold, which records the highest number of copies sold since the magazine's start in July 2010. In 2018, Kai was cast in KBS' melodrama "Miracle That We Met". On August 7, 2019, Kai was confirmed to be a member of SuperM, a "K-pop supergroup" created by SM Entertainment in collaboration with Capitol Records. The group's promotions are scheduled to begin in October and are aimed at the American market. Kai has been selected as the first Gucci Eyewear Men Global Ambassador in Korea. SuperM debuted with the group’s self-titled debut EP on October 4, 2019.