Dinah Manoff was born on January 25, 1956, in New York City to actress, director, and writer Lee Grant and screenwriter Arnold Manoff. She spent her childhood and teenage years in New York City and Malibu, California, attending the New Lincoln School and Santa Monica High School before studying at the Actors Studio.

Dinah Manoff is best known for her roles as Carol Weston on Empty Nest, Elaine Lefkowitz on Soap, Marty Maraschino in the film Grease, and Libby Tucker in both the stage and film adaptations of I Ought to Be in Pictures, for which she won a Tony Award.

In 1975, she made her first professional appearance providing one of the voices in the animated independent film Everybody Rides the Carousel. Her television debut came in 1976 with a guest appearance on Welcome Back, Kotter.

She continued to build her career with guest appearances on various television series and her first TV movie, Raid on Entebbe, in 1977. Her film debut came in 1978 as Marty Maraschino, one of the Pink Ladies, in the movie version of Grease.

Her Broadway debut came in 1980 as Libby Tucker in Neil Simon's play I Ought to Be in Pictures, for which she won the Tony Award for Best Performance by a Featured Actress in a Play. She reprised the role in the 1982 film version, starring opposite Walter Matthau and Ann-Margret.

She also appeared as Karen, the suicidal friend of Timothy Hutton's character, in the Oscar-winning film Ordinary People in 1980.

In 1988, Dinah Manoff began a seven-year stint as Carol Weston on the NBC sitcom Empty Nest, a role for which she is best known on television. She has also appeared in several other films, including Child's Play (1988), Backfire (1987), and Bloodhounds of Broadway (1989).

Dinah Manoff is married to Arthur Mortell, and they have three children: Dashiell, Desi, and Oliver Mortell.