Earl Kenneth Hines was born on December 28, 1903, in Duquesne, Pennsylvania, about twelve miles from Pittsburgh. His father, Joseph Hines, played cornet and led the Eureka Brass Band, and his stepmother was a church organist. Hines meant to follow his father on cornet, but blowing hurt behind his ears, so he took classical piano lessons instead, and by eleven he was playing organ in his Baptist church. At seventeen, with his father's approval, he left home to play piano for the baritone Lois Deppe and his Symphonian Serenaders at the Liederhaus, a Pittsburgh nightclub, for $15 a week and two meals a day. Deppe also used him as a concert accompanist, including on trips to New York, and in 1921 the two performed on the radio, reportedly the first African Americans to do so. Their first records together were four sides for Gennett in 1923, only two of them issued, one being Hines's own composition "Congaine." Around this time he also accompanied the singer Ethel Waters.

In 1925 Hines moved to Chicago, then the center of jazz, working at the Elite No. 2 Club before joining Carroll Dickerson's band, which toured the Pantages theater circuit to Los Angeles and back. In the poolroom of the Black Musicians' Union local on State Street he met Louis Armstrong, then 24 to his 21, and the two played the union's piano together. Armstrong was struck by the fast octaves of Hines's "trumpet-style" right hand, and the two became close friends. Armstrong joined Dickerson's band at the Sunset Cafe, and in 1927 it became his band, with Hines as musical director. That year Armstrong rebuilt his recording-only Hot Five and hired Hines for the piano chair previously held by his wife, Lil Hardin Armstrong. The 1928 sessions produced "West End Blues," "Tight Like This," "Beau Koo Jack," "Muggles" and the trumpet-and-piano duet "Weather Bird," recorded on December 5, 1928. After a plan with Armstrong and the drummer Zutty Singleton to run their own club fell apart, Hines took a midnight-to-six job with the clarinetist Jimmie Noone at the Apex Club, recording 14 sides with Noone in 1928. His first piano solos were cut late that year, eight for QRS in New York and seven for Okeh in Chicago, all but two of them his own compositions, among them "A Monday Date."

On December 28, 1928, his twenty-fifth birthday, Hines opened at Chicago's Grand Terrace Cafe leading his own big band, and for the next twelve years the orchestra, which he preferred to call his "Organization," was the house band there, usually 15 to 20 players and at times up to 28, doing three shows a night. The club was controlled by Al Capone's organization. Nightly coast-to-coast radio broadcasts made it reportedly the most broadcast band in America. The pianists who occasionally took his chair so that he could conduct included Teddy Wilson and Nat King Cole. Each summer the band toured, and in 1931 it was among the first large Black bands to travel extensively through the South. Its members over the years included the saxophonist Budd Johnson, the arranger Jimmy Mundy, the trumpeter Walter Fuller, the reed players Omer Simeon and Darnell Howard, the trumpeter and violinist Ray Nance and the trombonist Trummy Young.

The Grand Terrace closed suddenly in December 1940, and Hines took the band on the road full-time. Billy Eckstine sang with it from 1939 to 1943, and he and Budd Johnson helped bring modern players into the ranks. Charlie Parker joined in 1942 and Dizzy Gillespie around the same time, and Sarah Vaughan replaced Eckstine as the band's singer in 1943 and stayed about a year. Other alumni of the modern wing included the tenor saxophonists Gene Ammons and Wardell Gray, the trombonist Bennie Green and the drummer Shadow Wilson. Late-night jam sessions among these players during the 1942-44 recording ban helped seed bebop, though the band left little on record from the period; Duke Ellington later said the seeds of bop were in Hines's piano style. In 1944 Hines stood in as leader of the Ellington orchestra when Ellington fell ill. In July 1946 a car crash near Houston left him with head injuries that affected his eyesight for the rest of his life. He kept the big band going for two more years, and in 1947 he bought Chicago's El Grotto nightclub, which foundered and cost him about $30,000.

In early 1948 Hines joined Armstrong's All Stars, and he left in 1951 after three years in which, by his own account, he felt used as a sideman next to his old friend. He then led his own small groups, starting with a markedly modern lineup of Bennie Green, Art Blakey, the bassist Tommy Potter and the singer Etta Jones, and, according to AllMusic, a Dixieland band in Los Angeles and later San Francisco through the 1950s. By the early 1960s he had settled in Oakland, opened a tobacconist's shop, and come close to quitting music. In 1964 the critic Stanley Dance persuaded him to give a series of solo and quartet recitals at New York's Little Theatre, his first piano recitals, and the reviews turned him into a rediscovery. In 1966 he won the DownBeat International Critics Poll for its Hall of Fame and was named the magazine's top jazz pianist, a title he took five more times. From then until his death he recorded more than 100 LPs, sixteen of them in 1974 alone, toured Europe, South America, Asia and Australia, and in 1966 spent six weeks in the Soviet Union on a State Department tour, playing 35 concerts. A 1975 television documentary was filmed with him at the Blues Alley club in Washington, and in 1979 he was inducted into the Black Filmmakers Hall of Fame. He played solo at Ellington's funeral and twice at the White House. Hines passed away of a heart attack in Oakland on April 22, 1983, days after his last show, in San Francisco, and is buried at Evergreen Cemetery in Oakland.

Hines is regarded as the pianist who carried jazz piano from stride into swing. Working over loud bands on upright pianos without amplification, he developed the "trumpet style" right hand, a single hornlike line doubled in octaves and capped with tremolos, which could cut through a brass section, while his left hand dropped the steady stride pattern for accents and off-beat figures. He would run a phrase far away from the pulse, stop short, leave a silence, and land back in time, with harmonic detours that other pianists of his generation did not attempt. His own explanation was that he wanted to play on the piano what he would have played on the trumpet. Dizzy Gillespie said the modern piano style came from Hines and traced the roots of Bud Powell and Herbie Hancock to him, and Duke Ellington said the seeds of bop were in his playing. AllMusic lists Teddy Wilson, Jess Stacy, Joe Sullivan, Nat King Cole and, to a degree, Art Tatum among those he influenced, and Erroll Garner said that when people talk about greatness at the piano they talk about Tatum and Hines. His late solo records, dense and layered, with long medleys and constant reharmonizing, are the part of his catalog many critics rate highest, and he was known for walking into a studio and leaving ninety minutes later with an unplanned solo LP.