Wynton Charles Kelly was born in Brooklyn on December 2, 1931, the son of Jamaican immigrants. He started at the piano around age four with almost no formal instruction, and attended both the High School of Music & Art and Metropolitan Vocational High School in New York. His own account of his schooling was blunt: they would not give him piano, so he took up the bass and studied theory instead. He was working professionally by 1943, in rhythm and blues groups, and at fifteen he toured the Caribbean with Ray Abrams's band. His recording debut came at sixteen, on saxophonist Hal Singer's "Cornbread," a 1948 side that went to number one on the Billboard rhythm and blues chart. Between 1948 and 1950 he worked with Hot Lips Page, Eddie "Cleanhead" Vinson, and Eddie "Lockjaw" Davis. In 1951, still nineteen, he cut his first date as a leader for Blue Note, the ten-inch New Faces, New Sounds: Wynton Kelly Piano Interpretations (BLP 5025), with Franklin Skeete and Oscar Pettiford sharing the bass chair and Lee Abrams on drums. That same year he joined Dinah Washington's band, which is what first made his name; he played with Lester Young in the spring of 1952 and recorded with Dizzy Gillespie later that year.

The army interrupted all of it. Kelly was drafted in September 1952 and stationed at Fort McClellan, Alabama, where he recruited the pianist Duke Pearson into the Third Army's traveling show and by April 1954 was running it as musical director. He came out after two years and went straight back to work, playing on and off with Washington and Gillespie and touring with Charles Mingus from late 1956 into early 1957. The mid-1950s New York sessions pile up quickly: Billie Holiday's Lady Sings the Blues in 1956, the Blue Note debuts of Johnny Griffin and Sonny Rollins, Art Blakey's Theory of Art in April 1957, and Griffin's A Blowin' Session with Lee Morgan and John Coltrane. On October 28, 1957, at Reeves Sound Studios, he made one of the odder appearances in his catalog: on Abbey Lincoln's That's Him! he is credited on both piano and bass, having taken over the bass for a track when Paul Chambers was too drunk to play it. On March 25, 1958, at Beltone Studios, he played piano and organ on The Pepper-Knepper Quintet (MetroJazz E1004), the co-led date by Pepper Adams and Jimmy Knepper, with Doug Watkins on bass and Elvin Jones on drums, supervised by Leonard Feather. Two months before that, on January 31, 1958, he had recorded his first full-length leader album, Piano (Riverside RLP 12-254), with Kenny Burrell, Chambers, and Philly Joe Jones; it circulates just as often under its reissue title, Whisper Not.

In January 1959 he replaced Red Garland in Miles Davis's band, and he held the chair until March 1963. Cannonball Adderley described the hiring as a single blunt sentence: Kelly was sitting in when Garland arrived late, and Davis told Garland that Kelly had the gig. Six weeks later Kelly was in Columbia's 30th Street Studio for the first Kind of Blue session. Davis had built the album around Bill Evans, who plays on four of its five pieces, but gave the blues, "Freddie Freeloader," to Kelly. That March 2, 1959 date produced "So What," "Freddie Freeloader," and "Blue in Green"; the April 22 date produced "All Blues" and "Flamenco Sketches." Kelly's single track on the best-selling jazz album ever made is the fact most often attached to his name, and it undersells the four years of work around it: the 22-city European tour with the quintet in the spring of 1960, Someday My Prince Will Come (recorded March 7, 20, and 21, 1961), the two Blackhawk live volumes cut in San Francisco that April, and the Carnegie Hall concert of May 19, 1961.

The freelance work he did alongside the Davis job is where most of his best playing sits. Kelly Blue (Riverside RLP 12-298), recorded February 19 and March 10, 1959, put his trio with Chambers and Jimmy Cobb at the center and added Nat Adderley, Bobby Jaspar, and Benny Golson on two tracks. Kelly Great followed on August 12, 1959 at Fine Sound, with Wayne Shorter, Morgan, Chambers, and Philly Joe Jones; Vee-Jay printed the original sleeve with both the title and the pianist's name misspelled, and had Cannonball Adderley write the liner notes. On November 10, 1959 the Kelly, Chambers, Cobb trio backed Shorter's Vee-Jay debut Introducing Wayne Shorter; on November 24 and December 2 they cut most of John Coltrane's Coltrane Jazz for Atlantic, and the December 2 session also produced "Naima," the one track on Giant Steps that uses this rhythm section rather than the Tommy Flanagan group. Kelly is the pianist on Hank Mobley's Soul Station (1960), Roll Call (1960), and Workout (1961), on five Blue Mitchell albums for Riverside, and on Cannonball Adderley's Quintet in Chicago and Takes Charge. His first meeting with Wes Montgomery came in 1961 on Bags Meets Wes!, and the two made Full House live at Tsubo in Berkeley on June 25, 1962, with Johnny Griffin added on tenor.

When Kelly left Davis in March 1963, Chambers and Cobb left with him, and the Wynton Kelly Trio became a working band rather than a rhythm section for hire. Verve signed them after four Vee-Jay albums. Comin' in the Back Door (V-8576), recorded in May and November 1963 with Burrell and a Claus Ogerman string arrangement, yielded "Little Tracy," a calypso Kelly wrote for his daughter that reached number 38 on the Billboard rhythm and blues chart in May 1964. It's All Right! (V-8588) followed in 1964 and Undiluted (V-8622) was cut in a single day at Van Gelder Studio on February 5, 1965. That summer the trio toured with Montgomery, played Newport, and recorded Smokin' at the Half Note: two tracks live at the Half Note in June, the other three re-cut at Van Gelder on September 22, 1965 at Creed Taylor's insistence. A George Wein-organized tour of Japan came next. By September 1966, when the trio recorded Full View at Plaza Sound Studios for Milestone, Ron McClure had taken the bass chair. Two Left Bank Jazz Society concerts in Baltimore document the late group: November 12, 1967 with Hank Mobley and Cecil McBee, and September 22, 1968 with George Coleman and McClure. The trio also backed Joe Henderson on a 1968 live date issued as Straight, No Chaser. On August 4, 1968 in Chicago, Kelly, Chambers, and Cobb recorded together for the last time; Chambers's death in January 1969 ended the group, and Delmark issued the session as Last Trio Session.

The final two years were thin. Kelly worked with Ray Nance and as a soloist around New York, took what he could get, and made what appears to be his last studio session in the autumn of 1970 backing Dexter Gordon on The Jumpin' Blues. In April 1971 he traveled from New York to Toronto for a job with drummer George Reed and singer Herb Marshall. He telephoned his girlfriend to say he felt unwell, and on April 12 he suffered an epileptic seizure at the Westminster Hotel on Jarvis Street; Marshall found him in his room. He was 39 and reportedly left almost nothing. A memorial concert was held in New York on June 28 that year. Wynton Marsalis, born in 1961, was named after him.

Kelly's playing is immediately identifiable and hard to imitate convincingly: a crisp, forward-leaning touch, strongly dotted eighth notes, single-note lines that combine bebop vocabulary with blues phrases dropped in mid-sentence, and block chords used as punctuation rather than as filler. Jimmy Cobb, who sat behind him for a decade, described the effect as happy sounding all the time, with a West Indian kind of hop to it. What made him indispensable was the other half of the job. Philly Joe Jones said Kelly put down flowers behind a soloist and never wanted to steal in; Cannonball Adderley called him the world's greatest accompanist for a soloist, and Miles Davis framed his value structurally, saying that in Kelly he had a combination of Red Garland and Bill Evans and could therefore go any way he wanted. Evans himself, whose seat Kelly effectively took over, called him a fine accompanist who had by no means shown everything he could do. Kelly was also a fast, accurate reader who could memorize a part after one pass, which is why he turns up on so many one-off dates. His comping became a template: Chick Corea, Brad Mehldau, Monty Alexander, and Chucho Valdés have all named him directly, and his voicings are audible in Herbie Hancock's and McCoy Tyner's early work.