Amy London was born in Cincinnati, Ohio, in 1957. She decided at age seven that she wanted to be an entertainer after seeing a production of Fiddler on the Roof at Cincinnati's Shubert Theater, and grew up around music partly through her uncle Harry, who had played organ accompaniment for silent films at the city's Taft Theatre. She studied piano as a teenager, took up jazz piano in her senior year of high school, and at sixteen began working with the vocal coach Milt Wiener, a former music director at Cincinnati radio station WLW who had also coached Rosemary Clooney and Doris Day and who taught her to prioritize phrasing and storytelling over pure vocal technique. She earned a BA in opera from Syracuse University.

She moved to Manhattan in 1980 and spent her first years in New York working across genres: singing in big bands and Broadway pit choruses, performing with the choir at Trinity Church on Wall Street, co-founding a vocal group called Jazz Babies with singers Judy Niemack and Alexandra Ivanoff, touring as a backing vocalist with trumpeter Tom Browne, and singing backup for Charles Aznavour. From 1989 to 1992 she had a featured role in the original Broadway run of City of Angels, the Cy Coleman musical that won the 1990 Tony Award for Best Musical. She began teaching jazz vocals in 1984, while still building her own performing career.

During these same years she began a musical and personal partnership with the Israeli-born guitarist Roni Ben-Hur, whom she later married; the couple settled in Teaneck, New Jersey, and raised two daughters together. Their earliest joint recording, Two for the Road (Fivecat, 1994), is co-billed to both of them on the Discogs release credit, with pianist Chris Anderson filling out the trio; it was Ben-Hur's first record as a leader as well as London's first appearance on an album under her own name. The following year she sang on part of Ben-Hur's solo debut, Backyard (TCB Records, 1995), cut at Rudy Van Gelder's Englewood Cliffs studio with the Barry Harris Trio (Harris on piano, Lisle Atkinson on bass, Leroy Williams on drums), and in 1997 she guested on one track of his follow-up, Sofia's Butterfly, also engineered by Van Gelder. In the same period she sang alto with the vocal group New York Voices on Ancient Tower (1996), a setting of Rainer Maria Rilke's poetry composed by Robert Benford Lepley and narrated by Meryl Streep, later reissued as Visions Within.

London's first album billed to her alone, When I Look in Your Eyes (Motéma, 2007), was recorded at Bennett Studios in Englewood, New Jersey, with bassist Rufus Reid, drummer Leroy Williams, and pianists Lee Musiker and John Hicks; Ben-Hur also appears on the record as a credited guest. Her second Motéma release, Let's Fly (2011), paired her with pianist Tardo Hammer, bassist Santi Debriano and drummer Steve Williams, and included a title track she co-wrote with the vocalese singer Annie Ross. Bridges (Fivecat, credited by Discogs to 2014, though some contemporary press coverage places its release in November 2017), a retrospective drawing on sessions from across her catalog, brought together pianist Fred Hersch, drummer Victor Lewis, bassist Harvie S, saxophonist Bob Mintzer, guitarist Jack Wilkins, organist Lonnie Smith and several other veteran New York players across its fifteen tracks.

In 2015 London became the founding musical director of The Royal Bopsters, a vocal quartet built around the vocalese tradition, alongside singers Holli Ross, Dylan Pramuk and Darmon Meader (later succeeded by Pete McGuinness). The Royal Bopsters Project (Motéma, 2015) brought five of vocalese's living pioneers into the studio as guests: Jon Hendricks, Annie Ross, Mark Murphy, Bob Dorough and Sheila Jordan. The record earned four and a half stars from DownBeat, was named among the best jazz vocal releases of 2015 by DownBeat, JazzTimes, All About Jazz and Talkin' Broadway, and sold out a six-night release run at Birdland. The group toured with Sheila Jordan in 2019, appearing at Ronnie Scott's in London, the Half Note in Athens and the Newport Jazz Festival, and its second album, Party of Four (Motéma, 2020), again featured Jordan and Bob Dorough as guest vocalists along with bassist Christian McBride; it received four stars from DownBeat and was voted Best Vocal Jazz Group in the 2020 JazzTimes Critics' Poll.

London remains an active performer and educator. She was the featured vocalist for five years, 2021 through 2025, in saxophonist Mike Hashim's regular band at the Manhattan swing club Swing 46; that collaboration became the basis for her newest album, Alto Madness (2026), a tribute to Benny Carter and other alto saxophonists recorded at Teaneck Sound with Hashim, pianist Janice Friedman, guitarist Mark McCarron, bassist Ralph Hamperian, drummer Mike Campenni and trumpeter Ron Horton. She also curates the Milford Jazz Festival in Milford, Pennsylvania, now in its third year, and continues to teach: she was one of the founding architects of the jazz vocal BFA program at The New School in 1992 and remains on its faculty and that of the affiliated Mannes School of Music, along with City College of New York, Hofstra University, and the Vocal Jazz Academy she helped launch at Jazz House Kids in Montclair, New Jersey, in 2014. She also teaches annually at New York's Tritone Jazz Camp and at JazzWorks Canada in Quebec.

London's singing and her teaching both come out of the vocalese and vocal-group tradition that runs from Lambert, Hendricks and Ross through Jon Hendricks, Annie Ross, Mark Murphy and Bob Dorough, all of whom she recruited as guest elders on The Royal Bopsters' two albums rather than simply citing as influences. Her own vocal style favors close harmony blend and a swing-driven, standards-based repertoire over the more freely improvised end of jazz singing, and she has been as significant a figure in vocal-jazz pedagogy as in performance: she was one of the founders of The New School's jazz vocal BFA program in 1992, a rarity at the time among conservatory-level jazz programs, which had historically centered on instrumentalists.