Rachelle Stephanie Ferrell was born on May 21, 1961, in Berwyn, Pennsylvania, and grew up in the Philadelphia area. She began singing at six, studied violin at school and piano at home, and has said she thinks of herself as an instrumentalist first. Her father, an amateur jazz musician, filled the house with jazz, gospel and classical records, and in her mid-teens he bought her a piano on the condition that she learn it to a professional standard. Within six months she had her first paid job as a singing pianist; she had already been performing as a violinist since 13. At 18 she enrolled at Berklee College of Music in Boston to study composition and arranging, alongside classmates who included Branford Marsalis, Kevin Eubanks, Donald Harrison and Jeff Watts. She finished in a year and then taught music for the New Jersey State Council on the Arts, in a program that included Dizzy Gillespie, who predicted she would become a major force in jazz.

For about fifteen years from 1975 she paid the bills in clubs, church choirs, opera companies and recording studios, singing backup for Lou Rawls, Patti LaBelle, Vanessa Williams and George Duke, touring with Phyllis Hyman from 1988 and singing on a Miles Jaye album track, "Desiree." Record companies kept praising her and turning her down until, late in the 1980s, she sent a demo of her own pop songs to Blue Note's Bruce Lundvall, who then caught her live and heard a set of jazz material. He signed her to an unusual arrangement under which she would record one jazz album for Blue Note and one pop and urban album for its parent company, Capitol.

The jazz record came first. Her debut used a rhythm section of pianist Eddie Green, bassist Tyrone Brown and drummer Doug Nally, with Lenny White producing and guests including Wayne Shorter, Michel Petrucciani, Stanley Clarke and Terence Blanchard. It came out first in Japan in 1990 on the Somethin' Else label, and reached American listeners on Blue Note in April 1995 as First Instrument. She toured Japan and Europe from 1990 and played the Montreux Jazz Festival in four consecutive years in the early 1990s; a July 15, 1991 Montreux set later became most of her live album. Her self-titled 1992 Capitol album, mostly produced by George Duke, was a quiet-storm R&B and pop record on which she wrote ten of the thirteen songs and played piano on three, and which was certified gold by the RIAA. It sold slowly at first, and Capitol began promoting it heavily in 1994, when "With Open Arms" was released as a single. Her own songwriting leans toward R&B and pop, and her career has run on two tracks since: jazz records and festival sets on one, R&B and pop records on the other.

From 1995 to 1997 she toured and recorded with the George Duke Band, singing on his albums Illusions (1995) and Is Love Enough? (1997) and appearing in the concert film Live at Montreux 1997, and she sang "Moody's Mood for Love" with Quincy Jones, Brian McKnight, Take 6 and James Moody on Jones's 1995 album Q's Jook Joint. After a long dispute with a production company that kept her from recording, she returned in August 2000 with Individuality (Can I Be Me?), produced by herself, Duke and the guitarist Jef Lee Johnson. It reached number 1 on Billboard's jazz albums chart and number 16 on its R&B albums chart, and its singles "I Forgive You" and "Satisfied" both reached the top fifteen of the Adult R&B Songs chart. Live in Montreux 91-97 followed on Blue Note in April 2002, pairing her 1991 quartet set with 1997 performances, including two songs from a Charles Aznavour tribute night sung with members of the WDR Big Band Cologne.

She has made no studio album of her own since, though she has kept recording as a guest: "Wounds in the Way" for the 2006 soundtrack of Madea's Family Reunion, vocals on Duke's Dukey Treats (2008) and Dreamweaver (2013), two songs on Charles Aznavour's 2009 album with the Clayton-Hamilton Jazz Orchestra, and a feature on Lalah Hathaway's 2011 album Where It All Begins. She performed at the Capital Jazz Festival in 2014 and in its 2018 tribute to Phyllis Hyman. An album titled The Art and Soul of Rachelle Ferrell has been announced, and as of November 8, 2026 no release is documented. In August 2023 her management announced that she was dealing with health and life hardships.

Ferrell is a crossover artist in the plain sense: her best-selling and most-played records, the 1992 album and Individuality, are R&B and pop records, with gospel and classical training underneath, while her jazz identity rests on the Blue Note albums, her Montreux sets and her standards repertoire. Her calling card is range and control: a voice usually described as spanning six octaves or more, with a chest register that her ballads lean on, an extended whistle register, scat lines and improvised vocal percussion, and the habit, learned from years of four-set nights, of singing a lyric as if from inside it. She accompanies herself at the piano, writes much of her own material and arranges it, and cites her violin and piano training as the base of her musicianship. Her career has deliberately straddled two markets. AllMusic's Alex Henderson described her in the 1990s as wearing two hats, a straight-ahead jazz singer and a commercial R&B and pop singer in the vein of Anita Baker, with the self-titled Capitol album representing the second. Ferrell herself resisted being sorted into either bin, telling the press that being asked to choose between jazz and pop was like being asked to choose between her right leg and her left. Standards on her first album ("You Send Me," "You Don't Know What Love Is," "Bye Bye Blackbird," "My Funny Valentine") sit beside original songs, and her Montreux sets keep that mixture. Critics repeatedly compared her upper register to Minnie Riperton, and USA Today's reviewer likened her to Anita Baker and Dianne Reeves on the 1992 album.