After M*A*S*H, she appeared in a number of the director's projects, namely the films Brewster McCloud (1970), Welcome to L.A. (1976) (produced by Altman, directed by his protégé, Alan Rudolph), The Player (1992), and Prêt-à-Porter (1994), and the short-lived anthology TV series Gun (1997).

In addition to her work with Altman, Kellerman appeared in films such as Last of the Red Hot Lovers (1972), Back to School (1986), plus many television series such as The Twilight Zone (1963), The Outer Limits (1963 & 1965), Star Trek (1966), Bonanza (1966, 1970), The Minor Accomplishments of Jackie Woodman (2006), 90210 (2008), Chemistry (2011), and Maron (2013).

[2] Kellerman also contributed songs to the soundtracks for Brewster McCloud (1970), Lost Horizon (1973), Rafferty and the Gold Dust Twins (1975), and Boris and Natasha: The Movie (1992).

[6]: 8  Within a year, she appeared in a production of John Osborne's Look Back in Anger staged by Corey and featuring classmates Shirley Knight, Jack Nicholson, Dean Stockwell, and Robert Blake.

She debuted in Henrik Ibsen's An Enemy of the People,[6]: 55  followed by parts in a Pasadena Playhouse production of Leslie Stevens's The Marriage-Go-Round and Michael Shurtleff's Call Me by My Rightful Name (1962).

Three months after that, Kellerman played Mag Wildwood in the original Broadway production of Breakfast at Tiffany's, directed by Joseph Anthony and produced by David Merrick, which closed after four preview performances.

She also had turns as the severely beaten (and only surviving) victim of Albert DeSalvo in The Boston Strangler (1968), and Phyllis Brubaker (Jack Lemmon's materialistic wife) in the romantic comedy The April Fools (1969).

[19] Her next role was as a hostile, chain-smoking, sex-addicted woman who was trying to have an afternoon affair with Alan Arkin's character in Gene Saks' film adaptation of Neil Simon's comedy Last of the Red Hot Lovers (1972).

Bob was as stubborn and arrogant as I was at the time, but the sad thing is that I cheated myself out of working with someone I loved so much, someone who made acting both fun and easy and who trusted his actors.

Two years later, she played Mackinley Beachwood in Dick Richards' Rafferty and the Gold Dust Twins (1975), one of two women who kidnap driving instructor—and former United States Marine Corps gunnery sergeant—Rafferty (Alan Arkin), also singing "Honky Tonk Angels".

[22] Her next appearance was as Sybil Crane (a woman in the midst of a divorce) in The Big Bus, a parody of disaster films, followed by a role as a lonely real estate agent in the Alan Rudolph-directed and Altman-produced Welcome to L.A. (both 1976).

[23] At the end of the decade, Kellerman's roles included Maureen, a veteran vaudevillian, in Verna: USO Girl (1978); Veronica Sterling, a party-addicted socialite, in the made-for-television film She'll Be Sweet (1978); and Lise Bockweiss—one of several wives of Pasquinel (Robert Conrad) and daughter of Herman Bockweiss (Raymond Burr)—in the 12-episode miniseries Centennial (1978–1979).

Kellerman played Kay King, the pretentious and kooky mother of a lovelorn daughter (Diane Lane), in George Roy Hill's A Little Romance (1979).

Kellerman began the decade as Mary, a divorced middle-aged suburban mother struggling to raise her rebellious daughter (Jodie Foster) in Adrian Lyne's Foxes (1980); Martha, a six-times-married eccentric, in Bill Persky's Serial, and the silly-but-sophisticated Mrs. Liggett in Jack Smight's Loving Couples.

Her later roles included Mary, a child psychiatrist in a sadomasochistic relationship with a psychology professor (Stephen Lackman) after they meet by accident (literally) in Michael Grant's Head On, and a 1920s socialite in Kirk Browning's made-for-television film adaptation of Dorothy Parker's 1929 short story Big Blonde (both 1980).

From October 3 to November 15, 1980, Kellerman starred as Julia Seton in an Ahmanson Theatre production of Philip Barry's Holiday (directed by Robert Allan Ackerman) with Kevin Kline, Maurice Evans, and Marisa Berenson.

[24] On February 7, 1981, Kellerman hosted Saturday Night Live, appearing in four sketches ("Monologue", "The Audition", "Was I Ever Red", and "Lean Acres") and closing the show with Donna Summer's "Starting Over Again".

[26] Her next roles were a KGB-training-school warden in the made-for-television film, Secret Weapons (1985); the sadomasochistic Judge Nedra Henderson in Moving Violations (1985); Rodney Dangerfield's love interest in Alan Metter's comedy Back to School (1986); Julie Andrews' and Jack Lemmon's eccentric neighbor in Blake Edwards' That's Life (1986); a porn star trying to get into heaven in Meatballs III: Summer Job (1986); Kerri Green's mother in Three for the Road (1987), and an actress in Henry Jaglom's Someone to Love.

In 1997, Kellerman was scheduled to play the title role in Mrs. Scrooge: A Slightly Different Christmas Carol, a made-for-TV film version of Charles Dickens' novella.

On June 10, 1999, Kellerman joined actresses Kathleen Turner and Beverly Peele in a Planned Parenthood press conference supporting a proposed law introduced to the U.S.

[31] At the beginning of the century, Kellerman appeared in Canon Theatre's production of Eve Ensler's The Vagina Monologues with Teri Hatcher and Regina Taylor.

[33] In March 2002, Kellerman performed in Los Angeles' What a Pair, a benefit for breast cancer research,[34] joining singer-songwriter Julia Fordham for "Why Can't I".

[39] The next year, she played Dolores Montoya in Blank Theatre Company's Los Angeles revival of The Wild Party,[40] followed by the sexually-provocative Sandy in Susan Seidelman's Boynton Beach Club.

Kellerman sang Cole Porter's "My Heart Belongs to Daddy" with actress, singer and songwriter Kathleen "Bird" York at her third (and final) What a Pair concert.

Sally featured interpretations of songs by Linda Ronstadt, Kim Carnes, Aerosmith, Nina Simone, the Motels, Neil Diamond, Jackson Browne, Marvin Gaye, Dolly Parton, Jennifer Warnes, and James Taylor.

On July 7, 2012, Kellerman appeared with Tito Ortiz, Cary Elwes, and Drake Bell in an episode of the Biography Channel's Celebrity Ghost Stories.

[47] In September 2013 filmmaker Ellen Houlihan released a short film Joan's Day Out, in which Kellerman played a grandmother who escapes from her assisted-living facility to bail her teenage granddaughter out of prison.

[48] Kellerman made a return appearance in the second season of Maron in the episode "Mom Situation",[49] and as part of an Epix Network documentary celebrating the life of Robert Altman on August 6, 2014.

[55] In 1967, Kellerman's sister, Diana, came out as a lesbian and separated from her husband, Ian Charles Cargill Graham, who took full custody of the couple's daughter, Claire.

[1] She also dated screenwriters David Rayfiel and Charles Shyer, as well as journalist Warren Hoge, producer Jon Peters, and actor Edd Byrnes.