Mal Waldron was born Malcolm Earl Waldron on August 16, 1925, in New York City, to West Indian immigrant parents; his father worked as a mechanical engineer for the Long Island Rail Road, and the family moved to Jamaica, Queens, when Mal was four. He trained classically as a child before discovering jazz through the records of Charlie Parker, and went on to earn a B.A. in music from Queens College in 1949, studying composition under Karol Rathaus.

His professional break came through Charles Mingus, in whose Jazz Composers Workshop he played from roughly 1954 to 1956, appearing on the 1956 Atlantic session Pithecanthropus Erectus, one of Mingus's earliest and most influential albums as a leader — a relationship covered in full in Mingus's own JazzProfiles.com profile. From 1956 to 1958 he served as a house pianist for Prestige Records, a role that put him on dozens of the label's sessions and, by his own estimate, saw him composing more than 400 pieces during those years. His best-known composition, "Soul Eyes," debuted on the 1957 session Interplay for 2 Trumpets and 2 Tenors before John Coltrane's later recording made it a widely covered jazz standard.

From April 1957 until her death in July 1959, Waldron was Billie Holiday's regular accompanist, playing behind her on the landmark 1957 television broadcast The Sound of Jazz and on her 1958 album Lady in Satin; Holiday, in turn, became godmother to his first daughter. He paid tribute to her the following year with Left Alone (Bethlehem, recorded 1959, released 1960), built around a ballad the two had written together, with Jackie McLean guesting on alto saxophone.

In 1961 Waldron also worked in the short-lived quintet co-led by Eric Dolphy and trumpeter Booker Little, a partnership cut short when Little died that November at 23. That same year he led his own session with Dolphy, released as The Quest (recorded June 1961, issued 1962 on New Jazz), pairing Dolphy's alto saxophone and clarinet with Booker Ervin's tenor — the record most often cited as the high point of what's sometimes called his "first period" as a hard bop composer-pianist.

That period ended abruptly in 1963. A heroin overdose left Waldron in a breakdown so severe that, by his own account, he could not remember his own name, let alone how to play the piano; hospital treatment included a spinal tap and shock treatment. Physical recovery took roughly a year, and full recovery as a musician took two more — he relearned his own vocabulary by listening back to his old recordings, transcribing his own solos, and rebuilding his technique from those transcriptions until improvisation became possible again. The result was a fundamentally changed pianist: where the pre-1963 Waldron had been comparatively lyrical, the post-recovery Waldron built his style around dense repetition, angular voicings, and a spare, percussive left hand — the sound most listeners now associate with his name.

He left the United States for good in the mid-1960s, citing the cutthroat competitiveness of the American scene and the pay disparities Black musicians faced there. After time in Paris, Rome, Bologna, and Cologne, he recorded his first European album, the solo piano session All Alone (1966, GTA Records, Milan), and in 1967 settled in Munich, prompted in part by an offer from director Marcel Carné to score the film Trois Chambres à Manhattan. In 1969 he became the first artist ever released on a brand-new German label, ECM, with the trio album Free at Last (ECM 1001) — a catalog number that still marks the birth of one of jazz's most consequential record labels.

Europe made Waldron enormously prolific and, in time, only more mobile. He began touring Japan regularly from 1970, eventually spending up to two months a year there by the early 1980s; composed film scores including Sweet Love, Bitter (1967) and Tokyo Blues (1986); and worked constantly in small formats — trios, solo piano, and above all a decades-long duo partnership with soprano saxophonist Steve Lacy that ran from the 1970s to the year of his own death, documented on albums including the all-Ellington/Strayhorn Sempre Amore (1987) and one of his final recordings, the trio session One More Time (2002, with Lacy and bassist Jean-Jacques Avenel) — a relationship covered in full in Lacy's own JazzProfiles.com profile. Waldron described the duo format simply: jazz, he said, "is like a conversation... to do this face to face, it is more direct, stronger and more accurate."

In the 1990s he relocated from Munich to Brussels, where he lived for the rest of his life. He continued performing into his final weeks, giving his last concert in Lille roughly two weeks before he died. Waldron married twice and had seven children; he died of complications from cancer on December 2, 2002, in Brussels, at age 77.

Waldron's mature style is defined by the break: the fluid, harmonically curious "first period" pianist who cut sessions for Prestige and backed Billie Holiday gave way, after 1963, to a starker, more percussive player built on ostinato figures, dense repetition, and a spare, almost minimalist left hand — a sound critics have called hypnotic, brooding, and blues-drenched. That later style proved remarkably adaptable, working as comfortably in hard-bop small groups as in the freer, more open forms he explored across five decades in Europe, and it gave him a distinctive harmonic vocabulary built on unusual chord voicings and insistent rhythmic cells rather than conventional swing phrasing. His years as Billie Holiday's final accompanist gave him an unmatched, direct connection to one of jazz vocal music's most consequential figures, while his lifelong friendship and duo partnership with Steve Lacy pushed him toward the most stripped-down, conversational version of his music: two voices, no rhythm section, nothing to hide behind.