In 1935, Horne left dancing and became a singer in the black band Noble Sissle's Society Orchestra. She made her film debut in 1938 with "The Duke is Tops", an independent all-black film. In 1940, she joined Charlie Barnet and his Orchestra, one of the first white bandleaders who hired African-American musicians. Nonetheless, she left after one season, as touring with the band in racially segregated America proved quite exacting for her. Horne could not stay at the same hotel as the other band members, could not use the theatre's dressing room and had to change in the bus, and could not sit on stage with the other musicians between musical numbers.

In 1942, Horne signed a 7-yr contract with M-G-M, the first African-American performer ever to land a long-term contract with a major studio. Moreover, built into Horne's contract was the provision that she would not be playing domestics or jungle native roles. In fact, studio executives thought that she would be more marketable if they passed her off as Latin-American : she should change her name, learn Spanish, and study a new repertoire. When Horne refused this proposition, the studio appointed Max Factor to create an especially designed make-up to darken her skin - "Light Egyptian". Ironically, this "corrective" device turned against the very person for whom it had been designed, as the studio used it to paint white actors dark and gave them the parts that might have gone to Horne instead. During her tenure in Hollywood she made 13 films and except for the all-black cast "Cabin in the Sky" (1943) and "Stormy Weather" (1943), Horne appeared in featured specialty numbers without speaking lines. "I never felt like I really belonged to Hollywood. At that time, they didn't know what to do with me, a black performer. So, I usually just came on, sang a song, and made a quick exit," commented Horne (in the documentary "That's Entertainment III"). Her appearances were designed to exist independently of the narrative : musical sequences that could easily end up on the cutting room floor without compromising the story line. In fact, these scenes were often removed from the films when the pictures were shown to Southern audiences.

After playing Julie's role and singing "Can't Help Loving Dat Man" in an excerpt from "Show Boat" for "Till the Clouds Roll By" (1946), Horne had little doubt that she would be chosen to play that character again in MGM's remake of "Show Boat" (1951). Instead, Horne lost the part to her best friend Ava Gardner. Realizing that her film career was not going to bring any more than bit parts, Horne left Hollywood and went back to singing, performing in the top night spots.

While the Fifties brought tremendous success to Horne's singing career, she encountered serious political difficulties that barred her from any other professional engagements. She was blacklisted because of her left-wing associations (notably her friendship with Paul Robeson) and that meant no film work in Hollywood, no radio and television broadcasts, and no music recording. Horne was also listed in "Red Channels", a publication that kept a count of "subversive" people in the entertaining industry. By the mid-Fifties the situation improved : she was called back to Hollywood to appear in a film in 1956 ("Meet Me in Las Vegas"), and her name was lifted from "Red Channels" the year after. During the Sixties, Horne was actively involved in the Civil Rights movement. She returned to the stage in 1981 with "Lena Horne : The Lady and her Music", which became the longest-running one-woman show in the history of Broadway. She earned a special Tony Award, a Drama Desk Award, and a citation from the New York Drama Critics' Circle. She also returned to the screen occasionally : her most recent film was "That's Entertainment III" (1994). And she continued to record albums. Her latest one, "Lena Horne : Being Myself", was released this past June. Being herself, indeed.