After Graduating from college Johnson frequently performed in various comedy shows at the Upright Citizens Brigade Theatre in New York and Los Angeles, where he met Eric Edelstein. Shortly after Johnson and Edelstien wrote and performed thier comedy stage show This Is My Friend, at the Second city in L.A.
In 2006 Johnson and Edelstein worked with executive producers to create a half-hour improvised pilot for television based on their sketch show, also called
This Is My Friend.
In 2011, he landed a starring role as Nick Miller in the Fox sitcom New Girl, which was one of eight honorees in the "Most Exciting New Series" category at the Critics' Choice Television Awards, voted by critics who had seen the pilot.The series premiered to a strong audience of 10.28 million and to a positive critical reception.