From 2016-2017, Yook starred in the hit fantasy-romance drama Guardian: The Lonely and Great God. He also joined the cast for the reality-documentary show Law of the Jungle filmed in Sumatra, Indonesia. In August 2017, he participated in the digital single project, Piece of BtoB. He released the songs "Say It" and "Paradise", the latter having been personally composed and written by himself, on August 30. In late 2017, he joined the cast of the reality show, All The Butlers.