Born Carol Diahann Johnson in The Bronx, New York, she attended the New York City High School of the Performing Arts, along with schoolmate Billy Dee Williams.

Her family moved to Harlem, NY when she was one and a half years old.

Her first film assignment was a supporting role in Carmen Jones in 1954, playing a friend of the sultry Carmen.

Much later, her big break came when she became the first African American actress to star in her own television series in which she did not play a domestic worker, when Julia debuted in 1968. She was nominated for an Emmy Award for the role, and won the 1968 Golden Globe for "Actress In A Television Series".

Carroll's other television work includes appearances on shows hosted by Jack Paar, Merv Griffin, Johnny Carson and Ed Sullivan, and on The Hollywood Palace.

In 1959, she played Clara in the film version of Gershwin's Porgy and Bess along with such distinguished actors as Sidney Poitier, Dorothy Dandridge, Sammy Davis Jr. and Pearl Bailey. Opera singer Loulie Jean Norman dubbed Carroll's singing voice. All of the actors' singing voices were dubbed except for Pearl Bailey.

In 1974 she was nominated for an Academy Award for Best Actress for Claudine. She has also starred in the series Dynasty and The Colbys. Carroll commented at the time that the Aaron Spelling soaper splurged to dress her, whereas the wardrobe budget for Julia had been $50 (USD) for her nurse's uniform. She also had a recurring role on the NBC sitcom A Different World as Whitley Gilbert (Jasmine Guy)'s mother.

Carroll starred in the Canadian production of Andrew Lloyd Webber's musical version of the classic film Sunset Boulevard , playing the lead role, crazed silent movie star Norma Desmond, along with Rex Smith as Joe Gillis.

Carroll has been married four times, her last marriage a stormy one with singer Vic Damone from 1987 to 1996.

Diahann Carroll is a breast cancer survivor.