Melody Joy Gardot was born on February 2, 1985, in New Jersey, and spent much of her childhood in and around Philadelphia in the care of her Polish-immigrant grandmother, while her mother, a photographer, traveled for work. She started piano lessons at nine, and by sixteen she was playing in Philadelphia bars and clubs several nights a week, choosing repertoire she liked rather than what the room expected. She was studying fashion at the Community College of Philadelphia when, in November 2003, a car struck her as she rode her bicycle. The head, spinal and pelvic injuries kept her in a hospital bed for about a year and left her with memory problems and a lasting sensitivity to light and sound, which is why she has long worn dark glasses on stage.

Music became part of her rehabilitation. A physician who thought it might help her brain encouraged her to hum, then to sing into a tape recorder, and eventually to write. Unable to sit comfortably at a piano, she learned guitar while lying on her back, and because loud sound was painful she gravitated toward quiet records, including the bossa nova of Stan Getz. The songs she wrote in that period became the self-released 2005 EP Some Lessons: The Bedroom Sessions. Airplay on Philadelphia public radio, including WXPN, carried her recordings to Universal Music Group executives, and she signed with Verve Records. Her debut album, Worrisome Heart, first appeared independently in 2006 (with new recordings of EP songs and new material) and was reissued by Verve in 2007 and 2008, the latter the official release. In August 2008 she played the Newport Jazz Festival.

Her breakthrough came with My One and Only Thrill (2009, Verve), produced by Larry Klein with string arrangements by Vince Mendoza, a team best known for their work with Joni Mitchell. It debuted at No. 42 on the Billboard 200, reached No. 12 in the UK and No. 1 in Sweden, placed in the top five in France, Germany, Norway and French-speaking Belgium, and had sold more than 1.5 million copies worldwide by 2015. Three Grammy nominations went to its collaborators: Mendoza for the title-track arrangement, engineers Helik Hadar and Al Schmitt, and Klein as producer. In 2010 she was one of the guest singers on Charlie Haden's all-star vocal album Sophisticated Ladies and won the German Echo Jazz prize for international female singer, an award she took again in 2016.

The Absence (2012, Decca) was produced by the Brazilian guitarist and composer Heitor Pereira. The record leaned into samba, bossa nova, tango and Portuguese-language material, with Peter Erskine and Jim Keltner among the drummers, and it reached the top of the Billboard jazz albums chart, No. 33 on the Billboard 200 and platinum certification in France. She reunited with Klein for Currency of Man (June 2015), an all-original set of socially minded songs that pushed her toward blues and soul, with horns arranged by Jerry Hey, strings by Clément Ducol and a vocal choir; it also topped Billboard's jazz chart and earned a 2016 Grammy nomination in the Best Engineered Album, Non-Classical category. Live in Europe (February 2018, Decca), which she produced herself, gathered 17 performances chosen from more than 300 concerts played between 2012 and 2016.

Sunset in the Blue (October 2020, Decca), produced by Klein with orchestral arrangements by Mendoza and the Royal Philharmonic Orchestra, mixed originals with standards and featured guests including Till Brönner and Donny McCaslin; a bonus track, "Little Something," paired her with Sting. For "From Paris with Love" she recruited out-of-work musicians from around the world to record their parts at home in 2020 and paid them standard session rates. In 2022 she made Entre eux deux (Decca), an intimate duo album with the pianist Philippe Baden Powell, recorded in December 2021 in Paris and co-produced with Denis Caribaux. The Essential Melody Gardot, a Decca career compilation, followed in 2024, and in January 2026 she was the featured singer on "Misty" from Jeff Goldblum's album Still Blooming: Night Blooms. Away from the studio she has spoken at hospitals and universities about music therapy, and a music therapy program in New Jersey has carried her name since 2012.

Gardot sings in a low, breathy contralto and favors restraint, space and understatement over vocal display. Her records blend jazz with blues, bossa nova, French chanson, folk and artful pop, and her own songwriting, much of it intimate or cinematic in mood, is as central to her reputation as her interpretations of standards and chansons by writers such as Cole Porter, Édith Piaf and Jacques Brel. Her earliest listening in recovery centered on Stan Getz and the Brazilian songs of the late 1950s and early 1960s, and critics have compared her phrasing to Billie Holiday, Peggy Lee and Nina Simone, and her writing to Joni Mitchell and Laura Nyro. She sits at the pop-leaning edge of contemporary vocal jazz: AllMusic files her under Vocal Jazz and Vocal Pop, the Echo Jazz prizes and Billboard's jazz albums chart have recognized her, and her audience has been especially large in France, Germany, the Netherlands and Scandinavia, where she is often credited with bringing younger listeners to jazz.