Film:
* The Secret Life of Walter Mitty (1947) - Her film debut
* The Bachelor and the Bobby-Soxer (1947)
* The Girl from Jones Beach (1949)
* The Daughter of Rosie O'Grady (1950)
* The Man with My Face (1951)
* The Blue Gardenia (1953)
* The Scarlet Hour (1955)
* The Wild Party (1975)
* The Last Unicorn (1982) - Voice role as Molly Grue
* The Jewel of the Nile (1985)
* The Unbearable Lightness of Being (1988)
* The Player (1992)
* The American President (1995)
* The Santa Clause (1994) - as Mrs. Claus
* The Santa Clause 2 (2002) - as Mrs. Claus
Television:
* The Philco Television Playhouse (1950s) - multiple appearances
* The Colgate Comedy Hour (1950s) - multiple appearances
* The Adventures of Ozzie & Harriet (1950s) - multiple appearances
* Alfred Hitchcock Presents (1955-1962) - multiple appearances
* The Twilight Zone (1960-1964) - multiple appearances
* The Defenders (1961-1965) - multiple appearances
* The Bob Newhart Show (1972-1978) - multiple appearances
* The Love Boat (1977-1986) - multiple appearances
* Murder, She Wrote (1984-1996) - multiple appearances
* The Golden Girls (1985-1992) - multiple appearances
* L.A. Law (1986-1994) - multiple appearances
* The Simpsons (1989-present) - voice role as the "Old Lady" in several episodes
* Seinfeld (1989-1998) - as "Mrs. Steinbrenner" in several episodes
* Frasier (1993-2004) - multiple appearances
* ER (1994-2009) - multiple appearances
* Law & Order (1990-2010) - multiple appearances
* Grey's Anatomy (2005-present) - multiple appearances
* The Closer (2005-2012) - multiple appearances
This list is not exhaustive, but it showcases the breadth of Mariette Hartley's career, spanning decades and featuring appearances in some of the most iconic television shows and films of all time.