James Price Johnson was born February 1, 1894, in New Brunswick, New Jersey, to William H. Johnson, a store helper and mechanic, and Josephine Harrison, a maid who sang in her Methodist church choir and played piano by ear. His mother taught him first. The family moved to Jersey City and then, around 1908, to the San Juan Hill district of Manhattan's West Sixties, a dense Black and Afro-Caribbean neighborhood where Johnson heard ragtime, the shouts and ring dances brought north by Southern migrants, and the Harlem "ticklers" who played rent parties for a share of the door. He took his first professional job at Coney Island in the summer of 1912 and was working New York clubs steadily by 1913. From 1913 to 1916 he also studied formally with the Italian-born instructor Bruto Giannini, who drilled him in harmony, counterpoint, and classical fingering, and Johnson spent the rest of his life writing music that assumed both traditions.

The room that shaped his most famous piece was the Jungles Casino, a basement dance hall on West 62nd Street licensed as a dance school. Its regulars were Gullah and Geechee stevedores from Charleston, South Carolina, and the Sea Islands, working the Ward Line docks, and Johnson built his accompaniments around the dances they brought with them. He said plainly that the beat of "The Charleston" came out of that room. Beginning in May 1917 he cut player-piano rolls at a punishing rate for Metro Art, Universal, Perfection, Artempo, Rhythm, Arto, and eventually QRS: "Caprice Rag" and "Steeplechase Rag" that first month, "Daintiness Rag" in July, an Artempo roll of "Carolina Shout" in February 1918, and a QRS run through the early 1920s that carried his music to pianists who would never hear him play live. Scott E. Brown and Robert Hilbert's discography documents 37 roll sessions between May 1917 and February 1927, the last a duet with his former student Fats Waller. Johnson married Lillie Mae Wright in 1917, having met her in Newark three years earlier.

His disc career opened around August 1921 with "The Harlem Strut" for Black Swan (BS 2026), and on October 18, 1921, he returned to the studio for Okeh and recorded "Keep Off the Grass" and "Carolina Shout" (Okeh 4495, matrices 70259 and 70260). That coupling is routinely cited as the first jazz piano solo committed to disc, predating Jelly Roll Morton's Gennett solos by two years, and "Carolina Shout" became the test piece a young pianist had to pass. Duke Ellington and Fats Waller both learned it note for note off the QRS roll, slowing the mechanism and following the depressed keys with their fingers. Johnson led his own Harmony Eight for Okeh in December 1921, went to England with the "Plantation Days" revue in March 1923, and then wrote the score that made him famous: Runnin' Wild, with lyrics by Cecil Mack, which opened at the New Colonial Theatre on October 29, 1923 and introduced "The Charleston" to Broadway. The song outran the show, the decade, and its composer's control of it.

Through the middle and late 1920s Johnson was the accompanist Harlem's best singers asked for. On February 17, 1927 he and Bessie Smith recorded "Preachin' the Blues" and "Back-Water Blues" as a bare voice-and-piano duo (Columbia 14195-D), still among the most admired vocal accompaniments in jazz, and he returned to her on three further 1927 and 1929 dates. He backed Ethel Waters on "Guess Who's in Town" and "My Handy Man" in August 1928, and Waters later wrote that playing with him made a singer want to sing until her tonsils fell out. On April 27, 1928, W.C. Handy staged Carnegie Hall's first full evening of Black concert music, and its centerpiece was Johnson's Yamekraw: A Negro Rhapsody, orchestrated by William Grant Still. Johnson was contractually stuck in the pit conducting Keep Shufflin' that night, so Waller played the piano part. Johnson's own solo playing peaked on disc at a Brunswick session of January 21, 1930 that produced "You've Got to Be Modernistic," "Jingles," "Crying for the Carolines," and "What Is This Thing Called Love?" (Brunswick 4712 and 4762), four sides many collectors still treat as the summit of his recorded work.

He spent most of the 1930s composing rather than playing. Harlem Symphony came in 1932, Concerto Jazz-a-mine in 1935, an American Symphonic Suite built on Handy's "St. Louis Blues," and the one-act blues opera De Organizer, written with Langston Hughes around 1940 and given only one verified complete performance, at Carnegie Hall in May 1941. Almost none of this music was published or played again in his lifetime, and much of it was lost; the De Organizer manuscript surfaced only in 1997 in the Bentley Historical Library at the University of Michigan and was performed there in 2002. Johnson came back to the bandstand in 1939, playing solo at Cafe Society, appearing at both of John Hammond's From Spirituals to Swing concerts at Carnegie Hall (December 23, 1938 and December 24, 1939), and cutting a Columbia solo session on June 14, 1939 that yielded "Blueberry Rhyme," "The Mule Walk," and "If Dreams Come True." Columbia shelved most of it. Illness stopped him in the summer of 1940.

The war years brought his best-documented burst of recording. He cut solos for Moses Asch in July 1942, then two Blue Note solo dates on November 17 and December 15, 1943 that produced "Backwater Blues," "Carolina Balmoral," "Mule Walk," "Caprice Rag," and "Improvisation on Pinetop's Boogie Woogie." On March 4, 1944 he led James P. Johnson's Blue Note Jazzmen, with Sidney De Paris, Vic Dickenson, Ben Webster, and Sid Catlett, through "Victory Stride" and "Blue Mizz." Waller's death in December 1943 prompted two Decca sessions in April 1944 devoted entirely to Waller's songs, and two more in August and September 1944 devoted to his own. He played Eddie Condon's Town Hall concerts, appeared as a regular guest on Rudi Blesh's This Is Jazz broadcasts in 1947, and shared a Town Hall stage with Sidney Bechet, Pops Foster, and Baby Dodds in September 1946. A stroke that October knocked him out until the spring of 1947.

Johnson went to Los Angeles in 1949 for a production of his revue Sugar Hill, sat in with Kid Ory's Creole Jazz Band on a June 28 radio broadcast from the Beverly Cavern, and cut a handful of West Coast solos that August or September. His last preserved performance, a concert with a Sidney Bechet group on March 5, 1950, survives only on unissued acetates. A severe stroke in 1951 paralyzed him and ended his playing for good. He lived on his songwriting royalties, stayed at home for three years, and spent his final days in a Queens hospital, passing away on November 17, 1955 at 61. He was buried at Mount Olivet Cemetery in Maspeth, Queens, in a grave that stayed unmarked until 2009, when the James P. Johnson Foundation raised the money for a headstone. He had joined ASCAP in 1926; the Songwriters Hall of Fame took him in 1970, the Down Beat Jazz Hall of Fame in 1973, and the U.S. Postal Service issued a 32-cent James P. Johnson stamp on September 16, 1995. "Carolina Shout" entered the Grammy Hall of Fame in 2020.

Johnson took ragtime's written left hand and made it swing: a bass note on beats one and three answered by a mid-register chord on two and four, then deliberately broken up, so the pattern lurches into bass-bass-chord-bass sequences that throw the accent where the ear does not expect it. That elasticity is what separates stride from the ragtime it grew out of, and Johnson invented most of it. Over the top he ran orchestral right-hand writing, long chromatic runs, trills, tenths, and tightly constructed melodic strains built like rag sections rather than improvised choruses. He was also, uniquely among the early Harlem pianists, a trained composer who kept trying to write for orchestra, and the strain between the rent-party pianist and the symphonist runs through his whole career. Waller was his student outright and carried the technique forward; Ellington and Basie learned from his rolls and records; Art Tatum worked out his solos as a teenager in Toledo; and the stride left hand under Thelonious Monk's dissonances came out of the same tradition, learned in the same San Juan Hill blocks where Johnson had worked twenty years before Monk grew up there. Bud Powell, Oscar Peterson, and Teddy Wilson all sit downstream of him. The musicologist David Schiff called him "The Invisible Pianist," and the label has stuck for a reason: his songs are far better known than his name.