Born Jai Stephen Courtney on March 15, 1986, in Sydney, New South Wales, Australia, he grew up in the suburb of Cherrybrook. His mother was a teacher and his father worked for an electricity company; he had no show business connections in his family. Courtney developed an early interest in drama, participating in a state-sponsored drama program and school plays. He later attended the Western Australian Academy of Performing Arts (WAAPA), from which he graduated in 2008.