Casey Johnson made his debut as a screen actor with a small supporting role in the crime drama film "A Killer Walks Amongst Us" (2016). However, seeing as the film never received an American release, it wouldn't be until after Johnson's second project that he'd gain much notice.
Johnson next starred in "GLOW" (Netflix 2017-), a 1980s-set comedy series about the world of female professional wrestling. On the show, Johnson played a recurring role as Billy, a pizza delivery boy who develops a romantic relationship with one of the main characters, wrestler Justine, played by Britt Baron. "GLOW" launched Johnson to a costarring part in the high school drama series "Rise" (NBC 2018-), on which he was cast to play Gordy, the son of Josh Radnor's central character, high school drama teacher Lou Volpe.