Joëlle Léandre was born September 12, 1951, in Aix-en-Provence, France, and began playing double bass at age nine. She trained classically at her hometown conservatory before entering the Conservatoire National Supérieur de Musique de Paris, and by her late teens was already working as a substitute bassist in classical opera orchestras. A one-year scholarship took her to the Center for the Creative and Performing Arts at the University at Buffalo, where she met composer John Cage, a meeting that reoriented her entire career; she has said that hearing the swing bassist Slam Stewart on record was what first pulled her toward improvising rather than reading notation. Back in France, she worked for a period as a freelance double bassist inside Pierre Boulez's Ensemble Intercontemporain, playing under Boulez himself and under conductor Michel Tabachnik, and in 1981 she took part in a British project pairing choreographer Merce Cunningham with Cage. Both Cage and Italian composer Giacinto Scelsi wrote open-form solo works specifically for her: Cage's The Wonderful Widow of Eighteen Springs and Scelsi's four double bass solos, the latter documented on Okanagon (hat ART, recorded 1992/released 1993), a trio recording of Scelsi's chamber pieces for harp, double bass and tam-tam.

Léandre's move into free improvisation followed a chance encounter with guitarist Derek Bailey in New York in the early 1980s. By July 1982 she was playing with Bailey, trombonist George Lewis and saxophonist Evan Parker at a Paris loft session later issued as 28 Rue Dunois Juillet 1982 (Fou Records, 2014), and in May 1983 she was one of the featured improvisers at Bailey's Company Week at London's ICA, a five-day showcase documented on the Incus LP Trios (1986) alongside Bailey, Evan Parker, Peter Brötzmann, Vinko Globokar and others. She and Bailey later recorded the duo album No Waiting (Potlatch, 1998), taped live at Les Instants Chavirés in Montreuil in 1997. Her relationship with Anthony Braxton followed a similar arc: she joined his expanded ensemble, alongside Evan Parker, George Lewis, trumpeter Paul Smoker, vibraphonist Bobby Naughton and drummer Gerry Hemingway, for an October 8, 1988 performance at the Festival International de Musique Actuelle de Victoriaville, released as Ensemble (Victoriaville) 1988 (Les Disques Victo, 1989); nearly two decades afterward she and Braxton recorded the duo Duo (Heidelberg Loppem) 2007 (Leo Records, 2009). She also built a long duo relationship with soprano saxophonist Steve Lacy, culminating in One More Time (Leo Records, 2005), a Brussels concert from July 2002 during Lacy's farewell tour of Europe; its closing track is a phone message Lacy left on Léandre's answering machine asking that the recording be released, honored after his 2004 death.

Alongside those associations, Léandre built an equally important body of work with fellow bassists. She recorded the two-bass duo Contrabasses (Leo Records, 1998) with William Parker, later followed by Live at Dunois (Leo Records, 2009), and joined a bass quartet with Parker, Barre Phillips and Tetsu Saitoh for After You Gone (Les Disques Victo, 2004), recorded live at Victoriaville in memory of bassist Peter Kowald. In 1990 she co-founded the trio Les Diaboliques with Swiss pianist Irène Schweizer and British vocalist Maggie Nicols, a self-consciously feminist improvising unit that recorded the studio album Les Diaboliques (Intakt, recorded 1993) and the live Splitting Image (Intakt, recorded 1994 in Zürich). Pianist Marilyn Crispell became another recurring partner, in the collective quartets Quartet Noir (with saxophonist Urs Leimgruber and drummer Fritz Hauser, documented live at Victoriaville in 1999 and on 2005's Lugano) and the Stone Quartet (with trumpeter Roy Campbell and violist Mat Maneri, on DMG @ The Stone Volume 1, recorded 2006, and Live at Vision Festival, recorded 2010 and released on Ayler Records). She has also shared stages with John Zorn in New York's downtown improvising scene, including a joint bill at The Stone in 2010, though no studio or duo recording between them has been documented. Léandre spent a period teaching improvisation at Mills College in California, working alongside guitarist Fred Frith, with whom she also recorded the trio session Tempted to Smile (Spool, 2003) alongside violinist Jonathan Segel.

Léandre's connection to Israel runs through a single, well-documented date. In November 2007 she performed in Israel in solo, duo, trio and sextet settings; the recordings were produced by Kadima Collective in Jerusalem and released the following year as the two-disc Live in Israel (Kadima Collective, 2008). The sextet tracks pair her double bass and voice with tenor saxophonist Albert Beger, bass clarinetist Assif Tsahar, soprano saxophonist Ariel Shibolet, pianist Daniel Sarid and drummer Haggai Fershtman. Beger's own biographical materials, circulated by the Jerusalem Academy of Music and Dance and by All About Jazz, list Léandre among his notable collaborators; this profile confirms that connection is real and dates specifically to that 2007 Israeli tour and its 2008 release, rather than resting on the biographical mention alone.

She remains one of the most active figures in international improvised music, touring extensively across Europe, North America and Japan and continuing to record prolifically into her seventies. In 2023 the Vision Festival in New York gave her its Lifetime Achievement Award, marking fifty years of her career and making her only the second European musician so honored, after Peter Brötzmann; the festival performances were documented on the box set Lifetime Rebel: Joëlle Léandre's Lifetime Achievement Award, Vision Festival 2023 (RogueArt, 2024). Recent recordings include the duo Long Bright Summer with Evan Parker (RogueArt, 2025) and the solo/small-group set Flint (Fundacja Ensemblage, 2025).

Léandre plays the double bass as a full expressive voice rather than a rhythm-section instrument, routinely combining extended arco and pizzicato technique with wordless vocalizing, percussive body-of-the-instrument playing and vocal-instrumental dialogue within the same phrase. That vocabulary grew out of an unusually direct line between two worlds rarely bridged by one musician: notated contemporary composition, through her work in Pierre Boulez's Ensemble Intercontemporain and the pieces John Cage and Giacinto Scelsi wrote expressly for her, and free improvisation, through her decades inside Derek Bailey's Company circle and her duo and trio work with Anthony Braxton, Evan Parker, Steve Lacy and William Parker. Critics and colleagues consistently single her out as one of European improvised music's defining bassists and one of very few improvisers, on any instrument, equally comfortable premiering a Scelsi score and duetting freely with a saxophonist she has never played with before. Her founding of the explicitly feminist trio Les Diaboliques with Irène Schweizer and Maggie Nicols, and her outspokenness in interviews about the marginalization of women in improvised and jazz scenes, have also made her a frequently cited voice on that subject within the music.