Curtin became one of the original cast members for NBC's Saturday Night Live in 1975 and remained on the show until 1980. Curtin cohosted the shows Weekend Update segment, with Dan Aykroyd, after Chevy Chase left the show.
From 1984 to 1989, Curtin costarred with Susan Saint James in the television sitcom, Kate and Allie.
In 1993, Curtin and Aykroyd were reuinited in Coneheads, a full length motion picture based on the popular SNL characters of the same name.
From 1996 to 2001, Curtin costarred in the television sitcom, 3rd Rock from the Sun, with John Lithgow, Kristen Johnston, French Stewart and Joseph Gordon-Levitt.