With his guitar Lucille, B.B. King sang and played his way out of the Mississippi cotton fields and onto international concert stages. Squeezing and trilling the strings way up the neck with his amp cranked, Mr. King, who died May 14 at 89, made an indelible mark on Jimi Hendrix, Eric Clapton, Buddy Guy and Fleetwood Mac’s Peter Green.

“One of the things that enabled B.B. to have such a profound effect on generations of rock-blues guitarists, from Eric Clapton and Jimi Hendrix to the present day, was [his music’s] very accessibility — its emotional accessibility in the high-flying, single-string focus of his soloing, and its musical accessibility in the broad range of sources from which he drew,” blues historian Peter Guralnick said in a 2014 interview.

The guitar accounted for only part of Mr. King’s popularity. “The World’s Greatest Blues Singer,” as he often was introduced, could shout and exhort the blues in a harsh, blustery baritone like a backwoods preacher, then caress the words with a soft falsetto plea in the same verse.

He seamlessly wove his guitar phrases between his vocals almost as though the guitar and his voice were one instrument. He never played while he sang. Lucille always answered his voice but never accompanied it.

“He holds the same place in blues as Louis Armstrong did in jazz. He is an ambassador for the music,” Guralnick said.

Many of Mr. King’s blues contemporaries, such as Lightnin’ Hopkins, John Lee Hooker and Muddy Waters, consciously played to their rural roots, but Mr. King drew on gospel music and big-band jazz. As a consequence, he found a much wider audience.

Mr. King grew up in the Jim Crow South and lived to see the blues evolve into a musical hybrid. Performers, black and white, embraced his style as the distinctions between blues, rock and soul gradually blurred.

His career reflected an intense drive for self-improvement. Mr. King conquered a childhood stammer to become a radio performer in the late 1940s. After learning music by ear, he studied music theory from books between engagements. While averaging more than 300 shows a year, he still found time to study for an airplane pilot’s license.

He also struggled to earn respect for himself and for the blues, a genre that many African Americans deemed passe by the 1960s. At the Royal Theater in Baltimore, he said, black teenagers once booed him after loudly applauding acts such as the Drifters and Sam Cooke.

“My only ambition is to be one of the great blues singers and be recognized,” Mr. King told music journalist Michael Lydon in 1974. “If Frank Sinatra can be tops in his field, Nat Cole in his, Bach and Beethoven and those guys in theirs, why can’t I be great and known for it in the blues?”

His touring career began in the 1950s with one-nighters on the “chitlin’ circuit” — taverns and small theaters that catered to predominantly black audiences. Mr. King was a steady seller on the R&B charts with such hits as “Woke Up This Morning” (1953), “Every Day I Have the Blues” (1955), “Please Accept My Love” (1958), “Sweet Sixteen” (1960) and “Rock Me Baby” (1964).

The breakthrough

In the late 1960s, an aggressive new manager, Sid Seidenberg, pushed Mr. King into an entirely different set of venues just as blues-rock musicians such as Clapton and Paul Butterfield were fostering an awareness of blues among white listeners.

B.B. King performs in 2012. (Rogelio V Solis/AP)

Seidenberg booked the bluesman into the Fillmore West in San Francisco — Mr. King’s first engagement in front of a counterculture and rock audience — and Caesars Palace in Las Vegas, a venue more associated with pop stars such as Frank Sinatra and Dean Martin. The manager also lined up TV appearances on “The Ed Sullivan Show” and “The Tonight Show.”

At 45, after two decades of hits on the R&B charts and nonstop touring, Mr. King broke through on the pop charts in 1970 with “The Thrill Is Gone.”

The song had already been an R&B hit in 1951 for blues singer Roy Hawkins. Mr. King’s update set the doleful lyrics against an up-tempo, danceable rhythm pushed along by bassist Jerry Jemmott. With a contemporary beat and the addition of orchestral strings, the record marked a slight change in direction for Mr. King and brought him wide commercial success.

The record won two Grammys, first in 1970, then nearly two decades later in 1998, when it was named a Hall of Fame recording. In total, Mr. King received 15 Grammy awards and, in 1988, was given a lifetime achievement Grammy. In 1991, he was awarded the National Medal of Arts and four years later the Kennedy Center Honors. In 2006, President George W. Bush bestowed on Mr. King the Presidential Medal of Freedom, the nation's highest civilian award.

Although he was not a dancer or physical entertainer like James Brown or Jackie Wilson, Mr. King developed a strong rapport with audiences by conversing with them. His stories were wry but almost sermonic in style, and were often told from the viewpoints of both sexes:

“Ladies, if you’ve got a man, husband, whatever you wanna call him,” he said on a concert recording, “and he don’t do exactly like you think he should, don’t cut him because you can’t raise him over again.”

“And fellas, I want say to you, if you got a wife, a woman or whatever you wanna call her, and she don’t do like you think she should, don’t go upside her head. That don’t do but one thing. That make her a little smarter — she won’t let you catch her the next time.”

Sharecropper’s son

Riley B. King was born Sept. 16, 1925, on a plantation near Itta Bena, Miss., to a sharecropping family. He said he never knew what his middle initial stood for; his stage name, B.B., was short for Blues Boy, from his early radio billing as the Beale Street Blues Boy.

Mr. King’s parents split up when he was 4, and his mother died when he was 9. Mr. King ran away from his father’s home and settled in Indianola, Miss., supporting himself by picking cotton. He discovered blues through 78-rpm records by singers Lonnie Johnson and Blind Lemon Jefferson.

A minister taught him the rudiments of the guitar and, at 18, Mr. King joined a local gospel quartet. He later busked on Beale Street in Memphis with a cousin, Delta blues guitarist Bukka White.

Mr. King bought an electric guitar after seeing a performance by bluesman T-Bone Walker. He cajoled his way onto a live radio broadcast in Clarksdale, Miss., hosted by singer and harmonica player Rice Miller, better known as Sonny Boy Williamson.

Williamson allowed Mr. King to perform on the air and asked listeners to call the station if they liked his music. Unbeknown to Mr. King, Williamson had booked himself two jobs at local juke joints, one paying $12 and the other $100, on the same night. Williamson called the lower-paying venue to cancel and instead offered up the services of Mr. King, the “new sensation” who was “burning up the phone lines.”

“He said, ‘I’m going to send him down in my place,’ ” Mr. King once recalled. “He told me, ‘You better play good, boy, because if you don’t, you’ll have to answer to me.’ . . . I liked it very much, because it was my job to entertain the ladies while the fellers went in the back and played cards.”

It was in this period that he took to calling his many guitars Lucille.

“Lucille got her name in a nothing town by the name of Twist, Arkansas,” he told music writer Lydon. “We were playing some club, and some guys were fightin’ and they knocked over a kerosene barrel and burned the place down. I almost got killed going back in to save my guitar, and when I found out the fight was over a gal named Lucille, I named my guitar that to tell me to keep her close and treat her right.”

Mr. King first recorded in 1949 — as a singer, not a guitarist — and was later brought to Modern Records, a Los Angeles record label, by its Memphis-based talent scout, Ike Turner. Turner recorded Mr. King’s first hit in 1951 with “Three O’Clock Blues,” in the back room of the Memphis YMCA.

By 1955, Mr. King was touring nationally with his own 10-piece band — an impeccably attired unit with a large horn section. Many of Mr. King’s earliest recorded songs were credited to Mr. King and “Taub,” “Ling” or “Josea”, pen names for Jules and Joe Bihari, the non-musician brothers who co-owned the Modern and Crown record labels. Although his records were on the R&B charts, Mr. King grew frustrated with the label owners’ cavalier approach to publishing and their practice of relegating his albums to the 98-cent budget bins.

In 1963, Mr. King contracted with the larger ABC Records and, two years later, released “B.B King Live at the Regal.” The album, one of Rolling Stone magazine’s “Top 500 Greatest Albums of All Time,” captured his live act before a predominantly black audience on Chicago’s South Side. Critics cited the way the singer and the audience “had church” — the audience screaming and talking back in response to his songs.

Although most of his songs dealt with male-female relationships, some addressed other concerns. “Why I Sing the Blues” (1969), co-written with Dave Clark, put the blues in the context of black history and the civil rights struggle. “Never Make Your Move Too Soon” (1978), written by Joe Sample, reflected the high-roller lifestyle of Las Vegas, Mr. King’s home in later years.

Fellow blues singer Bobby “Blue” Bland, who had known and idolized Mr. King since their respective youths in Memphis, did two live albums with him in the late 1970s.

In 1988, Mr. King sang with U2 on “When Love Comes to Town” from the band’s album “Rattle and Hum.” The song’s video introduced him to a younger generation of fans. Its success also generated Mr. King’s duets with rock, pop and hip-hop performers on albums such as “Deuces Wild” (1997). Among his most popular collaborations was a recording with Clapton, “Riding With the King” (2000).

Offstage life

Mr. King struggled with a weight problem and was diagnosed with Type 2 diabetes in the 1980s. In later years, his condition forced him to perform in a chair. At the time of his death, from complications of the disease, Mr. King was in hospice care at his Las Vegas home. His attorney, Arthur Williams Jr., confirmed the death to the Associated Press.

In recent decades, Mr. King became a multimillionaire from his many television commercials for Burger King, Wendy’s, Northwest Airlines, Texaco and other companies.

In the 1990s, he opened an eponymous nightclub on Memphis’s redeveloped Beale Street, later adding clubs in New York, Nashville and Orlando. In 2006, the B.B. King Museum and Delta Interpretive Center in Indianola opened with exhibits that set his life in the context of world events.

His marriages to Martha Denton and Sue Hall ended in divorce. In “Blues All Around Me,” Mr. King said he had 15 children from various relationships. Eleven survive, according to the Associated Press. One of his sons worked with him as a valet, and a daughter, Shirley King, is a blues singer in Chicago.

Mr. King felt compelled to continue touring, almost as if the hard road that led to the top could never end. “If I don’t keep doing it, keep going, they’ll forget me,” he told the New York Times in 2003.

He often reminded people of those hard times — and the hard road — when he told the story of the 1949 fire in which he nearly lost his guitar.

“I usually say you can get another guitar but not another B.B. King.”