The daughter of a musician, Walter was raised in Astoria, Queens, and made her stage debut at the Bucks County Playhouse in a production of the Paddy Chayefsky's "Middle of the Night". By 1961, she was on Broadway in "Advise and Consent". After a few more small roles, film and TV would beckon, but Walter would occasionally return to the stage. In 1970, she performed in a New Orleans production of "The Women" and in 1988, she returned to Broadway (and later L.A.) in Neil Simon's "Rumors", alongside her second husband, actor Ron Leibman. Walter made her screen debut in Robert Rossen's "Lilith" (1964), as Warren Beatty's old flame who marries Gene Hackman rather than await Beatty's return from Korea. Other roles have included the widow of Braverman, a grade-B intellectual whose death triggers reminiscences from his cronies in "Bye, Bye Braverman" (1968). Despite her chilling portrayal of a murderous woman with a fixation for Clint Eastwood in "Play Misty for Me", it took ten years before she was seen onscreen again, in the pallid comedy "Going Ape!" was again on the big screen. Walter subsequently was the social hostess and a presidential aspirant's wife with the campy name of Kay Mart in "Tapeheads" (1988). More recently, Walter had almost a cameo as a young grandmother in "Ghost in the Machine" (1993), one of the first features to find terror in virtual reality and was the college president and object of scorn in Hart Bochner's uneven comedy "PCU" (1994). She also enjoyed a plumb suporting turns in writer-director Tamara Jenkins' appealing comedy "The Slums of Beverly Hills" (1998) and writer-director Greg Pritikin's "Dummy" (2002).

The small screen has proven more hospitable. As many actors have, Walter began her career on a soap opera, portraying Julie Morano on CBS' "Love of Life" from 1962-65. Segueing to primetime, she played the musician wife of district attorney William Shatner in the short-lived "For the People" (CBS, 1965). She introduced the character of "Amy Prentiss" on an episode of "Ironside" and NBC gave her a limited episode series (rotating airings with Peter Falk's "Columbo", Dennis Weaver's "McCloud" and Rock Hudson's "McMillan and Wife") in 1974-75. Although it broke ground with a female chief of detectives solving crimes, the show cushioned her appeal by having the character say she was doing her job out of sense of duty and dedication rather than to make a feminist statement. As the dedicated cop who was also raising a young daughter (Helen Hunt), Walter won a 1975 Emmy as Best Actress in a Limited Series. series for her work as Amy Prentiss. Other series gigs have included a take-charge dame on Norman Lear's short-lived syndicated series "All that Glitters" (1977) and a recurring role on "Trapper John, M.D.", as the title character's ex-wife which earned her an Emmy nomination. Walter went on to play the bitch of "Bare Essence" (NBC, 1983) and the tart-tongued hairdresser mother of a girl pregnant by a lapsed Amish in "Aaron's Way" (NBC, 1988). She was on NBC again in the short-lived series "The Roundtable" (1992) and voiced the mama dinosaur on "Dinosaurs" (ABC, 1991-94). She returned to the world of daytime drama joining the long-running serial "One Life to Live" as Eleanor Armitage in 1996-1997. Although her return to primetime TV in the panned sit-com "Oh Baby" (1998-2000) flopped, Walter was subsequently triumphant in her role as the self-centered, vindictive mother Lucille Bluth in the critically hailed Fox sit-com "Arrested Development" (2003 - ).

Walter has been doing TV longforms since 1969 when she co-starred in "The Immortal" and "Three's a Crowd", both for ABC. In 1972, she was memorable as a calculating inmate in "Women in Chains" (1972). Walter first performed in miniseries with "Arthur Hailey's 'Wheels'" (NBC, 1978), was memorable as Maggie McGregor in "Scruples" (ABC, 1981) and has long been one of the most active guest stars on TV episodics. She earned another Emmy nomination for a 1976 installment of "The Streets of San Francisco" and appeared as different characters in multiple episodes of that series, along with "Barnaby Jones", "The F.B.I.", "Love American Style," "The Love Boat," "Magnum P.I.," "Murder, She Wrote," "Coach" and "Jack & Jill." The actress has also leant her throaty vocals to TV commercials and animated shows and specials.