Nala Sinephro was born in 1996 and grew up on the outskirts of Brussels, in a house beside a forest that her parents renovated: her mother was a classical piano teacher, and her father is a jazz saxophonist with roots in Martinique and Guadeloupe. The family visited Martinique at Christmas, and she later spent long stretches there. She started on piano and also played fiddle and violin, learning folk songs by ear. As a teenager she had a tumor removed from her jaw, spent a stretch in Brussels clubs absorbed in hard electronic dance music, and then moved to an arts high school with a jazz department. There, at about sixteen, she found a fellow student's pedal harp in a practice room and began playing it in secret. A jazz summer camp in Spain led to a place at Berklee College of Music in Boston, where she paid her way as a live sound engineer and stayed for a year.

She moved to London in 2017, left a second jazz college after a short time, and found her footing through jam nights and the South London collective Steam Down, where she met the saxophonist Nubya Garcia. She worked with the London Contemporary Orchestra and from June 2020 hosted her own show on NTS Radio. The first set of compositions for what became her debut was lost with a hard drive in April 2018; she rented a harp, started again, and held recording sessions beginning that August. The music was recorded across 2018 and 2019 at Pink Bird, a small studio in Wanstead in east London, and at home, in the wake of her recovery from a serious illness, and she has called the process medicinal.

Space 1.8 appeared on Warp Records on September 3, 2021, after she joined the label that year. She composed, produced, engineered and mixed it, playing pedal harp and modular synthesizer, with Garcia, James Mollison of the Ezra Collective and Ahnansé on saxophone, Lyle Barton on piano and keys, Shirley Tetteh on guitar, Jake Long and Eddie Hick on drums, Rudi Creswick and Twm Dylan on double bass, and Dwayne Kilvington, known as Wonky Logic, on synth bass. Pitchfork called it a benchmark in ambient jazz and placed it 24th on its list of the 50 best albums of 2021; Metacritic's aggregate was 85 from seven reviews. Earlier that summer NTS issued a one-sided 12-inch of a live set recorded at Real World Studios with Hick and Kilvington, limited to 250 copies, and she remixed Garcia's "Together Is a Beautiful Place to Be." In autumn 2021 she played her first full-band concert since the album's release, at the Horniman Museum in south London, with Hick on drums.

Her second album, Endlessness, came out on Warp on September 6, 2024, preceded by the single "Continuum 1" on August 7. All ten tracks are titled "Continuum" and run about 45 minutes in total. She produced, mixed and engineered it with Rick David and wrote the string arrangements, recorded at Air Studios and played by the group Orchestrate. The band was largely her London circle: Garcia and Mollison on saxophones, Sheila Maurice-Grey on flugelhorn and trumpet, Barton and Kilvington on keyboards and synthesizers, and the drummers Morgan Simpson and Natcyet Wakili. Metacritic recorded universal acclaim (83 from 13 reviews), the album topped the UK Jazz & Blues Albums Chart, and it appeared on year-end lists including the Guardian's 50 best albums of 2024 (number 30) and Crack's top 50 (number 3). At the 2025 Libera Awards, which honor independent music and were presented on June 9, 2025, it shared the Best Jazz Record award with Kamasi Washington's Fearless Movement.

In 2025 she wrote the score for The Smashing Machine, Benny Safdie's A24 drama about the mixed martial artist Mark Kerr, starring Dwayne Johnson and Emily Blunt. The film premiered at the Venice Film Festival on September 1, 2025, and opened in the United States on October 3, the day the eight-track score appeared on Warp; vinyl and CD editions followed in 2026. In 2026 Space 1.8 also returned as a double-LP pressing marking its fifth anniversary. As of early November 2026 her releases are the two Warp albums, the score, the live 12-inch and a few singles and remixes. She is based in London.

Sinephro writes at the piano, then layers pedal harp and modular and other synthesizers over improvisations by a rotating group of London jazz players, and she records and mixes much of it herself. The music is slow, spacious and built from repeating figures and long tones, close to what critics call ambient jazz: Pitchfork described Endlessness as dissolving the divide between ambient music and jazz, while Space 1.8 mixes ballad-like saxophone playing, beat-driven passages and beatless synthesizer washes, with field recordings such as birdsong from Martinique. She has said her synthesizers are tuned to 432 Hz. Reviewers set her beside the spiritual jazz of Alice Coltrane and Pharoah Sanders, though she told the Guardian that she came across Coltrane's music only after starting the album, and told Pitchfork that she learned of ambient figures such as Jon Hassell, Harold Budd and Eberhard Weber after finishing it. She has also said she dislikes being reduced to "the harp lady" or to a genre label and thinks of herself first as a composer. AllMusic describes her work as a fusion of ambient and spiritual jazz, and her collaborators come from the London scene around Garcia, Mollison, Maurice-Grey and Barton.