Eartha Mae Keith was born on January 17, 1927, in North, South Carolina. After her mother's death she was sent to Harlem to live with a relative, Mamie Kitt, and she attended Metropolitan Vocational High School in New York. In the summer of 1944 she left school at seventeen, spent a season as a wartime farm worker in upstate New York, and returned to the city that September to audition for the Katherine Dunham Company, the first African American modern dance company in the United States. She won a scholarship and, after six months at the Dunham school, made her professional debut with the company in the 1945 Broadway variety show Blue Holiday. Dunham then secured a Broadway run for Carib Song, which opened at the Adelphi Theatre on September 24, 1945, and Kitt's singing began to set her apart from the dancers around her.

She toured the United States with the Dunham company for several years. When the troupe went to London in 1948 and on through Europe, Kitt stayed in Paris in 1949 and built a career as a nightclub singer, performing Afro-Cuban songs and working rumba movements into her act. A March 1950 report in the New Pittsburgh Courier described her radio, television and concert appearances with American jazz musicians in Paris, naming Coleman Hawkins, Buck Clayton and Doc Cheatham. A 1950 Paris session credited to Kitt with Doc Cheatham and his trio produced four recordings that stayed unreleased until a 1985 Swing Disques compilation. That June, at the Edouard VII Theatre, Orson Welles cast her as Helen in Time Runs, his one-act take on the Faust story, staged under the double title The Blessed and the Damned, with Duke Ellington reported to have agreed to supply the music. Welles once called her the most exciting woman in the world.

Her breakthrough in the United States came in the Broadway revue New Faces of 1952, where she introduced "Monotonous" and "Bal, Petit Bal," and she signed with RCA Victor. Her first records for the label, made with Henri René and His Orchestra, made her a hit-maker within a year. She recorded "Uska Dara," her version of the Turkish folk song "Kâtibim," on March 13, 1953, and "Santa Baby," which Joan Javits and Philip Springer had been commissioned to write for her that August, on October 5, 1953. "C'est si bon," sung in French, and "I Want to Be Evil" came the same year. The ten-inch RCA Victor Presents Eartha Kitt reached No. 2 on the pop albums chart, the 1954 EP That Bad Eartha reached No. 5, and "Santa Baby" peaked at No. 4 on Billboard's best-selling singles chart. She had six US Top 30 entries in the early 1950s, and "Under the Bridges of Paris" reached No. 7 on the UK singles chart in 1955. She spoke four languages and sang in seven, and her 1956 autobiography, Thursday's Child, later lent its title to a 1999 David Bowie song.

Her most direct contact with the jazz tradition came in 1958. In Paramount's W. C. Handy film St. Louis Blues, which premiered that April, she played the singer Gogo Germaine opposite Nat King Cole in the title role, with Ella Fitzgerald and Cab Calloway also in the cast. RCA Victor issued an album of songs from the film credited to Kitt with Shorty Rogers and His Giants, with Leonard Feather writing the liner notes, clarinetist Matty Matlock arranging most of the numbers, and a band that included Stan Wrightsman on piano, Al Hendrickson on guitar, Morty Corb on bass and Nick Fatool on drums. She then recorded for Kapp and MGM, with albums that included Revisited (1960), arranged by Maurice Levine, and Bad but Beautiful (1962), and for EMI Columbia in Britain, where Love for Sale (1965) used Tony Osborne's orchestra.

On January 18, 1968, Kitt attended a White House luncheon hosted by First Lady Lady Bird Johnson on the subject of juvenile delinquency. When the discussion turned to the Vietnam War and young people's unrest, she criticized the war, saying that the country was sending its best young people to be shot and maimed. Mrs. Johnson replied that a war was no reason to be uncivilized. The exchange was widely reported, her bookings in the United States reportedly dried up, and she spent much of the next decade performing in Europe and Asia. In 1975 the New York Times reported, in a story by Seymour Hersh, that the Central Intelligence Agency had kept a file on her, and Kitt gave the paper permission to print parts of it. She was invited back to the White House for a reception hosted by President Jimmy Carter on January 29, 1978, and that year returned to Broadway in Timbuktu!, which brought her the first of two Tony Award nominations; the second came for The Wild Party in 2000.

Her comeback on records was a dance single. "Where Is My Man," produced by Jacques Morali and released in the United States on StreetWise in late 1983, reached No. 7 on the Billboard dance chart and No. 36 in the UK, and it led to the 1984 album I Love Men and a new audience in nightclubs. In 1987 she replaced Dolores Gray as Carlotta in the London West End production of Sondheim's Follies, and in 1989 she charted in Britain again with "Cha Cha Heels," recorded with Bronski Beat. The jazz side of her recording life returned in the 1990s. Thinking Jazz (ITM, 1991) paired her with the clarinetist Rolf Kühn, the pianist Joachim Kühn, tenor saxophonist Jerry Bergonzi, bassist Jesper Lundgaard and drummer Daniel Humair, and included "God Bless the Child," "Lullaby of Birdland" and "My Funny Valentine." Back in Business (DRG, 1994), a program of standards with a Sondheim title song, was nominated for a Grammy at the 38th Annual Grammy Awards in 1996, in the traditional pop vocal category. Her only other Grammy nomination was in the children's recording category, for the 1968 spoken-word album Folk Tales of the Tribes of Africa.

In the 2000s she reached a younger audience as a voice actor, most prominently as the villain Yzma in Disney's The Emperor's New Groove and its follow-ups, work that won her an Annie Award in 2000 and Daytime Emmy Awards. She kept performing in New York cabaret rooms such as the Café Carlyle, recorded as Live from the Café Carlyle (DRG, 2006). In April 2008 she appeared at the Cheltenham Jazz Festival in England, and the concert was released as an album and DVD later that year. She passed away from colon cancer on Christmas Day 2008 at her home in Weston, Connecticut, at the age of 81. Her star on the Hollywood Walk of Fame dates from February 1960, South Carolina observes January 17 as Eartha Kitt Day, and in 2013 the jazz singer René Marie released I Wanna Be Evil (With Love to Eartha Kitt) on Motéma, with trumpeter Etienne Charles in her band, described as the first full tribute album to Kitt.

Kitt was a cabaret and theatre performer first, and she is covered here as a crossover figure, not as a core jazz singer. AllMusic files her under vocal music, with traditional pop and show-music styles, and a reviewer of her Cheltenham concert noted that she was not a traditional jazz artist even while praising the set. What gives her a place alongside jazz is where she worked and what she sang: a Paris nightclub scene that, by press report, put her on bills with American jazz musicians, a 1950 session with Doc Cheatham's trio, the film repertoire cut with Shorty Rogers's band, and a catalogue of Cole Porter, Fats Waller and Duke Ellington songs that runs through to her last concerts.

Her sound was a low, purring, deliberately theatrical delivery that treated each lyric as a short scene, and it moved across languages: French, Spanish, Turkish, German, Swedish and Italian songs all turn up on her records, along with a Philippine song, "Waray-Waray," that she learned phonetically on a 1963 tour. She trained as a dancer with the Dunham school before she was known as a singer, and movement stayed central to her act. The press compared her early on to Josephine Baker as another American performer who built a career in Paris, and critics kept describing her in feline terms, an image that carried into her 1967 turn as Catwoman in the television series Batman. The best evidence for the musician underneath the persona is the later work with players such as the Kühn brothers and Daniel Humair on Thinking Jazz, where she sings Billie Holiday's "God Bless the Child" and Cole Porter's "Night and Day" in front of a modern jazz quintet. AllMusic's related-artists list for her includes Dinah Washington, Nancy Wilson and Morgana King.