Horne died at New York-Presbyterian/Weill Cornell Medical Center, a spokeswoman said. No cause of death was given.
As a singer, Horne had a voice that jazz critic Don Heckman described in a 1997 profile in The Times as "smooth, almost caressing, with its warm timbre and seductive drawl — honey and bourbon with a teasing trace of lemon."
She was, Heckman wrote, "one of the legendary divas of popular music" — a singer who "belonged in the pantheon of great female artists that includes Ethel Waters, Billie Holiday, Ella Fitzgerald, Sarah Vaughan and Carmen McRae."
Horne, 80 at the time and cutting a new album, took a different view.
"Oh, please," she said. "I'm really not Miss Pretentious. I'm just a survivor. Just being myself."
When Horne first began dancing in the chorus at the Cotton Club — three shows a night, seven nights a week for $25 a week — she did so to help out her financially troubled family during the Depression.
By the time she arrived in Hollywood for a nightclub job in 1941, she had been a vocalist for the Noble Sissle and Charlie Barnet orchestras, had done some recording and was a cabaret sensation at the prestigious Cafe Society Downtown club in New York's Greenwich Village.
She created a similar response, performing at the Little Troc, a small club on the Sunset Strip, where, according to one news account, "she has knocked the movie population bowlegged and is up to her ears in offers."
Signed by MGM to a seven-year contract in an era when no other blacks were under long-term contracts at the major movie studios, Horne went on to become one of the best-known African American performers in the country.
With her copper-toned skin, strong cheekbones and dazzling smile, she was a breakthrough on the silver screen — "Hollywood's first black beauty, sex symbol, singing star," as Vogue magazine described her decades later.
"I was unique in that I was a kind of black that white people could accept," Horne once said. "I was their daydream. I had the worst kind of acceptance because it was never for how great I was or what I contributed. It was because of the way I looked."
Refusing to play maids and other stereotypical roles offered to black actors at the time, Horne appeared in a nonspeaking role as a singer in her first MGM movie, "Panama Hattie," a 1942 comedy musical starring Red Skelton and Ann Sothern.
That set the tone for most of her screen appearances in the '40s, a time in which she appeared in more than a dozen movies, including "I Dood It," "Swing Fever," "Broadway Rhythm" and "Ziegfeld Follies."
In most of them, she had only cameos as a singer, who was typically clad in a glamorous evening gown and singing while leaning against a pillar. It became her on-screen trademark.
"They didn't make me into a maid, but they didn't make me into anything else either," she wrote in "Lena," her 1965 autobiography. "I became a butterfly pinned to a column singing away in Movieland."
Horne's musical numbers usually were shot independent of the films' narratives, making them easy to be deleted when screened in the Jim Crow South.
Two exceptions were the all-black musicals in which she was one of the stars: "Cabin in the Sky" and "Stormy Weather," both released in 1943.