Erroll Louis Garner was born June 15, 1921 in Pittsburgh's Hill District, the youngest of six children and a twin (his brother Ernest was born the same day). Music was already in the house: his older brother Linton Garner, born in 1915, became a working pianist and arranger too. Erroll started picking out tunes at three by copying what he heard his older siblings being taught, and when the family's piano teacher discovered he was reproducing pieces by ear rather than reading them off the page, the lessons ended. He never learned to read music, and he never pretended otherwise. Asked about it later, his standard answer was that no one can hear you read, a line that supplied the title of the 2013 documentary about him. He was on Pittsburgh radio station KDKA at seven as part of a children's group, working Allegheny riverboats by eleven, and attended George Westinghouse High School, whose alumni also include Billy Strayhorn and Ahmad Jamal. In 1937 he joined saxophonist Leroy Brown's band. The Pittsburgh musicians' union refused him membership because he would not work from standard notation, a decision it reversed in 1956 by making him an honorary member.

Garner left for New York in the summer of 1944 and was recording within months. His earliest documented sessions were made not in a studio but in the Manhattan apartment of the Danish jazz writer and producer Timme Rosenkrantz across November and December 1944, mostly solo, and those recordings surfaced years later as Blue Note's five-volume Overture to Dawn series. He worked 52nd Street in Slam Stewart's group, cut sides with Stewart and with tenor saxophonist Don Byas, and moved to Los Angeles in 1946. There, on February 19, 1947 at C.P. MacGregor Studios, his trio with bassist Red Callender and drummer Harold "Doc" West backed Charlie Parker on the Dial date that produced "Cool Blues" and "Bird's Nest," and cut its own titles the same day. Garner was not a bebop player and never claimed to be, which is part of what makes that session such an odd and durable document. A solo date at Studio Technisonor in Paris on May 15, 1948 yielded "Early in Paris" and "These Foolish Things," and by April 1948 he was leading a trio at the Three Deuces on 52nd Street with Oscar Pettiford on bass and J.C. Heard on drums. William P. Gottlieb photographed him at that club in the summer of 1948. By 1949 DownBeat's poll had named him the year's best pianist and he was headlining the Apollo.

Martha Glaser became his manager in 1950 and stayed his manager, and eventually his producer and the executor of his estate, until his death. She was unusual in the business: Garner was her only client, and the two of them enforced a booking policy that refused segregated venues outright at a time when that cost money. Under Glaser he moved from clubs into concert halls and onto television, appearing on the Ed Sullivan, Steve Allen, Johnny Carson and Dick Cavett shows, and in 1958 he became the only jazz musician the classical impresario Sol Hurok ever took on. Two records from the mid-1950s did most of the work. On July 27, 1954, at Universal Recording in Chicago with Wyatt Ruther on bass and Fats Heard on drums, he recorded "Misty," a tune he had composed in his head on a flight into Chicago after watching a rainbow through haze, and which he could not write down. It became one of the most recorded songs of the century after Johnny Burke added a lyric and Johnny Mathis had a hit with it in 1959. Then on September 19, 1955, at Sunset School in Carmel-by-the-Sea, California, a concert he played with bassist Eddie Calhoun and drummer Denzil Best was taped by Will Thornbury for Armed Forces Radio. Glaser found the tape, Columbia producer George Avakian approved it despite the primitive sound, and it went out as Concert by the Sea. It sold over a million dollars at retail by 1958 and remains one of the best-selling jazz albums ever made.

The Columbia relationship then collapsed into the most consequential lawsuit of his career. Glaser had signed him to a five-year Columbia deal in 1956 containing a clause almost unheard of at the time: Garner personally had to approve any recording of his that the label released. In 1960, with the contract under renegotiation and Avakian gone from the company, Columbia began issuing material from his backlog anyway, including Swinging Solos, The One and Only Erroll Garner and The Provocative Erroll Garner. Garner sued. Columbia countersued in federal court, and he had to post a $40,000 bond, raised with help from friends, to keep an injunction alive while he was effectively barred from recording. After close to three years the New York Supreme Court found for him. He took a cash settlement reported at $265,297.55, recovered the physical masters and the ownership rights to his unreleased Columbia recordings made after June 1, 1956, and Columbia recalled the unauthorized pressings. It is widely described as the first case in which a recording artist sued a major label and won.

What he did with the money mattered as much as the verdict. Garner and Glaser used Octave Records to own his masters outright and license finished albums to major labels for distribution, an arrangement that ran the opposite way round from every standard record deal of the period. Twelve albums came out under it over the next fifteen years, each carrying "a product of Octave Records, Inc." on the sleeve: Dreamstreet (1961) and Closeup in Swing (1961) through ABC-Paramount, One World Concert (1963, taped in performance at the Seattle World's Fair) and the A New Kind of Love film score through Reprise and Mercury, then a run through MGM with A Night at the Movies (1965), Campus Concert (1966, recorded at Purdue), That's My Kick (1967) and Up in Erroll's Room (1968). The last of those is a brass-and-reeds date arranged by Don Sebesky with Pepper Adams on baritone saxophone and Phil Ramone among the engineers. Feeling Is Believing followed on Mercury in 1970 with George Duvivier and Jerry Jemmott sharing the bass chair, then Gemini (1972) and Magician (1974) on London. Three of these drew Grammy nominations: Dreamstreet at the 1962 ceremony, Up in Erroll's Room in 1969 and Feeling Is Believing in 1971. He never won one in his lifetime. Drummer Harvey Mason spent four months in his touring group in 1970, one of many young players who passed through.

Garner's health broke down after Magician. His last public performance was on February 20, 1975 at Mr. Kelly's in Chicago, and he passed away in Los Angeles on January 2, 1977 at 55, buried in Pittsburgh's Homewood Cemetery. Glaser spent the rest of her life keeping the catalog in print, and after her own death in 2014 her niece Susan Rosenberg took it on. The Erroll Garner Archive went to the University of Pittsburgh and the Erroll Garner Jazz Project launched on what would have been his 94th birthday, June 15, 2015. The reissue programme that followed has been substantial rather than token: The Complete Concert by the Sea (2015), a three-disc expansion with eleven previously unreleased performances that was Grammy- and NAACP Image Award-nominated and took the Jazz Journalists Association's historic record of the year; Ready Take One (2016) on Legacy, fourteen unreleased studio tracks from 1967, 1969 and 1971 co-produced by Geri Allen; Nightconcert (2018) on Mack Avenue, a midnight set from the Royal Concertgebouw in Amsterdam on November 7, 1964 with Calhoun and drummer Kelly Martin; the twelve-album Octave Remastered Series across 2019 and 2020, each title restored from analog masters with an unreleased bonus track; and the Symphony Hall Concert (2021), taped in Boston on January 17, 1959. In 2025 the Recording Academy gave him a posthumous Trustees Award.

Garner's left hand kept a flat, strumming four-to-the-bar chord pulse, close to a rhythm guitarist's, while his right hand landed consistently and deliberately behind it, a delay wide enough that musicians nicknamed the effect the "Russian Dragon" for the rushing and dragging it set against each other. He began in the stride tradition of Fats Waller and James P. Johnson and kept a good deal of it, layered with the lighter swing-era touch of Teddy Wilson and Earl Hines, an orchestral density borrowed from the big-band writing he had absorbed off records by Duke Ellington and Jimmie Lunceford, and harmonic colour that listeners regularly compare to Debussy and Ravel. His trademark was the introduction: a long, rubato, sometimes deliberately misleading preamble that gave no clue what standard was coming until the tempo dropped in. He was 5 feet 2 inches tall and played sitting on a stack of telephone directories, even at Carnegie Hall, humming and grunting audibly throughout. Because he could not notate anything, his roughly 200 published compositions had to be transcribed by other hands from his playing. The influence is easy to trace by name: Ahmad Jamal and Oscar Peterson were contemporaries working nearby territory, while Ramsey Lewis, Don Patterson, Jan Lundgren and Hiromi Uehara have all named Garner's records among the first things that pulled them toward jazz.