Ms. James was reported to have been diagnosed with dementia and leukemia. Her illnesses were made public as part of a court battle between her husband and her children concerning $1 million of the singer’s fortune, in part to cover her health expenses.
Ms. James attracted a broad following in the 1960s with her interpretations of jazz-inflected pop. Many of her songs, especially her 1961 string-backed version of the big-band-era pop standard “At Last,” are frequently heard on film and television soundtracks.
She influenced later singers from Janis Joplin to Bonnie Raitt. Raitt called her “the bridge between R&B, blues and pop singing. . . . Like Ray Charles, Etta brought the passion of gospel, R&B and gutbucket raw soul music into the mainstream in a way that very few people have ever crossed over.”
Ms. James made more than 40 albums and received the 1994 Grammy for best jazz vocal performance for “Mystery Lady: Songs of Billie Holiday.” She also experimented with rock music and was the opening act for the Rolling Stones in the late 1970s and early 1980s.
She saw herself foremost as a blues musician. In her 1995 autobiography, “Rage to Survive,” Ms. James wrote, “No matter how pop or schmaltzy a song, I can’t help but put a gospel and blues hurting on it.”
She often made a connection between her music and her anguished life, which included heroin addiction, drastic weight fluctuations and a troubled childhood.
She had been born to a 14-year-old single mother with a rebellious streak. Ms. James once wrote that if her mother was going to be bad, “I was going to be superbad.” And so she smoked marijuana, snorted cocaine and shot heroin. She associated with gangsters and pimps. She was arrested for forging prescriptions and writing bad checks. When not in jail, she said, she was involved with abusive men, some of whom nearly beat her to death.
She said the Betty Ford Center weaned her off drugs in the late 1980s; her cocaine habit began while on tour with the Stones, she said.
Even during the worst of times, Ms. James recorded well-received albums, and reviewers noted how her personal turmoil seemed to enhance her singing.
She said the song “Feeling Uneasy” on the 1974 album “Come a Little Closer” illustrated her experience undergoing drug treatment. Critic Richie Unterberger called the performance one of her career highlights, emphasizing the “wrenching, near-wordless scat-moan vocal over a suitably languorous, melancholy blues-jazz arrangement.”
Ms. James told the trade publication Billboard in 2001: “I don’t pick a song ’cause I think the music sounds cool. . . . I don’t want to sing ‘Fly me to the moon and let me swing amongst the stars.’ I want to sing something that either I’ve experienced or that I know is real.”
She was born Jamesetta Hawkins on Jan. 25, 1938, in Los Angeles. For years, she insisted her father was pool shark Rudolf Wanderone, known as “Minnesota Fats,” a habitue of L.A.’s Central Avenue jazz clubs. Her paternity was never resolved, even after she confronted the billiards player in his Nashville apartment in 1987.
She was raised by her mother’s landlady, a woman named Mama Lu, who took her to a local Baptist church, where she fell in love with singing. When Mama Lu died in 1950, Ms. James went to live with relatives in San Francisco but was largely unsupervised.
“I went from being this nice little church girl to living in a rooming house,” she told the Los Angeles Times. “I just turned incorrigible, drinkin’ wine, smokin’ weed and running the streets.”
Though weaned on church music, she said she began to like the blues “and the feeling it gave me. It gave me a naughty-girl feeling.” She recalled her mother’s fury when she came home one day and found her daughter listening to a 78 rpm of Guitar Slim’s “The Things That I Used to Do.” Her mother preferred Holiday and insulted her daughter’s taste. Ms. James claimed her mother never saw her perform until the late 1980s.
Ms. James hung out in gangs and began singing on the street in a cappella groups. One of them, the Peaches, provided her with her lifelong nickname, “Miss Peaches.”
In the early 1950s, she met bandleader and promoter Johnny Otis, who rechristened her by a simple flip of her first name. He guided her early career, leading to her first rhythm-and-blues hit,“Roll With Me, Henry” (1955). The tune, which she wrote, was a suggestive musical reply to Hank Ballard and the Midnighters’ “Work With Me, Annie.”
The song was released on Modern Records as “The Wallflower” to cloak the sexual theme. Singer Georgia Gibbs sang a sanitized version called “Dance With Me, Henry” that was a pop-chart success, and Ms. James said she was incensed about receiving no credit.
Ms. James toured with Little Richard and Bo Diddley and was a frequent performer on the black theater circuit. In 1960, she joined a major label for blues artists, Chicago-based Chess Records, and by the end of the decade began earning favorable comparisons with Aretha Franklin.
Label owner Leonard Chess reportedly thought Ms. James had a mass appeal that eluded many on his roster of primarily male, Delta blues musicians. He took special interest in guiding her career, which led to such broadly popular albums as “At Last!” The title song, written in 1941 by Harry Warren and Mack Gordon, had been a big-band standard.
Besides the title song, the album contained many songs with which she would remain associated: “Trust in Me,” “All I Could Do Was Cry
” and “I Just Want to Make Love to You.
Ms. James and Chess were portrayed as lovers in the 2008 movie “Cadillac Records,” a fictionalized account of the record label’s history, but Ms. James said their relationship was strictly business. Contemporary singer Beyonce Knowles played Ms. James in the movie.
Ms. James’s latter albums included “Time After Time” (1995), “Heart of a Woman” (1999) and “Blue Gardenia” (2001). She was inducted into the Rock and Roll Hall of Fame in 1993 and the Blues Foundation’s Blues Hall of Fame in 2001.
In 1969, she married Artis Mills. Besides her husband, survivors include two sons from previous relationships, Donto James of Moreno Valley, Calif., and Sametto James of Riverside; and several grandchildren.
Ms. James sang at the opening ceremony of the 1984 Summer Olympic Games in Los Angeles and remained a concert performer through recent years. She described herself as “statuesque”; she had once stood at 5-foot-11 and weighed well over 200 pounds. After a series of health reversals toward the end of her life, she was forced to use a wheelchair onstage.
Nevertheless, she still gave audiences some of the randy onstage writhing they had come to expect during her most vibrant days — sucking her thumb, cupping her breasts and growling her voice.
She frequently was caustic about where many modern singers had taken the rhythm-and-blues music she pioneered, naming Paula Abdul and Janet Jackson, for example, as hotshot dancers with little to recommend them vocally.
“A lot of people think the blues is depressing, but that’s not the blues I’m singing,” she told the Los Angeles Times in 1992. “When I’m singing blues, I’m singing life. People that can’t stand to listen to the blues, they’ve got to be phonies.”
Staff writer Terence McArdle contributed to this report.