Nicki Parrott was born in 1970 in Newcastle, New South Wales, an industrial port city two hours north of Sydney, and grew up in a house where her parents played classical records constantly. She started piano at four and added flute soon after, kept both through school, and at twelve joined the Marching Koalas, a 150-strong Australian youth band that took her to the Rose Parade in Pasadena. The bass arrived by a family accident. Her sister Lisa, a saxophonist, had a band with school friends and told her she did not want a flute player but did need a bassist. There was a double bass in the school band room; Parrott took it home and it had three strings. A neighbour told her not to worry about the fourth because nobody hears the low notes anyway, and she played G, D and A for a while before working out that everyone else had four. She taught herself at first, buying Charlie Parker and Miles Davis records and transcribing the bass lines, and the jazz camps in Sydney gave her a peer group that included the trumpeter James Morrison, the drummer Andrew Dickeson and the trombonist Adrian Mears. After high school she moved to Sydney to study at the New South Wales Conservatorium of Music, and began working with Mike Nock, Dale Barlow, Paul Grabowsky, Bernie McGann and the ensemble Ten Part Invention, and touring Australia with the American trumpeters Bobby Shew and Chuck Findley. When Ray Brown came through Sydney to play with Morrison she phoned his hotel and asked for a lesson. He said it was his day off and he wanted to play golf, took her number, called back, and asked how fast she could get there. She was twenty. What she took from the hour was that a sound belongs to the player and not the instrument: he picked up her bass and it still sounded like Ray Brown. John Clayton taught her on the same visiting basis.

A three-month trip in 1991, built out of a week at the Caveau de la Huchette in Paris with an Australian band, ended with a month in New York staying at Hotel 17 and walking to Bradley's, the Village Gate and Fat Tuesday's. She went home, worked for two years, and applied to the Arts Council of Australia for a grant to study privately with Rufus Reid, whose bass method she had read. It was one of two grants given that year, and she arrived in New York in May 1994 on a ten-month clock, telling her mother at Sydney airport she would be back in six months. She stayed nearly thirty years. The bandleader Kit McClure sponsored her artist visa, which put her into a working life that was much wider than the double bass: reggae dates, parties, and eight years of Wednesday nights with a rhythm-and-blues band on the Upper West Side, playing electric bass and singing backing vocals. Broadway pit work followed, in Jekyll & Hyde, You're a Good Man, Charlie Brown, Avenue Q, Imaginary Friends and Summer of '42, which she has described plainly as the place a musician goes to get their reading together and pick up union work with a pension. Sherrie Maricle heard her and made her the full-time bassist of the DIVA Jazz Orchestra for about three years, and Parrott is on On The Brink, the 1999 Arbors debut of Five Play, DIVA's small group. Her earliest traced session, though, is neither: it is Pentatomic, cut for the Australian label Rufus Records at Systems Two in Brooklyn on February 9 and 10, 1995, on which she plays acoustic bass and contributes two compositions. Around the same period she began a decade of touring with the clarinettist David Krakauer's klezmer bands, four albums for the French label Label Bleu, most of it on electric bass, and much of it in Paris. One credit from these years sits well outside everything else she has done: on October 28, 2000 she played bass in the premiere run of William Parker's commissioned large-ensemble piece "For Fannie Lou Hamer" at The Kitchen, a performance eventually issued on AUM Fidelity in 2015.

In June 2000 she went with the session guitarists John Tropea and David Spinozza to sit in at Les Paul's Monday night at the Iridium. Paul knew the guitarists and called all three up. After a few tunes he said the two men could go and sit down but the girl should stay. He made a joke at her expense, she made one back, and Paul's bassist Paul Nowinski asked her to sub while he went on tour. Two or three weeks later Paul told her he would see her the following Monday, and she was in the band. She stayed until his death in August 2009 at ninety-four, playing the residency almost every Monday of the decade. The Iridium chair put her on the same small bandstand as Paul McCartney, Keith Richards, Jeff Beck, Slash, Steve Miller, Richie Sambora, Tony Bennett, José Feliciano and Tommy Emmanuel, and the Monday-night regulars included astronauts and actors as well as guitarists. It also made her a singer. Paul stopped her in the middle of a bass solo one night and asked whether that was all she was going to do, and whether she sang. She said she sang in the shower, remembered the lyric to "Deed I Do," and sang it; he tapped her on the shoulder and told her to leave it in. From then on singing was part of the job, and she used it to answer his onstage teasing by writing short songs about him. She has been careful to say that the gender jokes were an act: offstage he called her during the week to talk about pickups and sound, and encouraged her without qualification.

The records under her own name started with The Awabakal Suite, cut in one day in New York on January 26, 2001 with her sister Lisa, Kevin Hays on piano and Rufus Reid producing. It carries "Come And Get It," the tune that had won the Jazz Action Society's annual song competition in 1992. Six years later she began the two catalogues that define her leader work. People Will Say We're In Love, a duo with the pianist Rossano Sportiello, came out on Arbors Records in 2007 and was named by The New Yorker one of the ten best jazz CDs of the year, and Moon River, her first record as a featured singer, appeared on the Japanese audiophile label Venus Records in December of the same year. Moon River won Swing Journal's Best Vocal Album award for 2007 and Fly Me To The Moon took the same prize the following year; Black Coffee won the magazine's Gold Disc in 2010. Venus kept her working at a rate few singers sustain: four seasonal albums in a single year, songbooks devoted to Nat King Cole, Burt Bacharach and the Carpenters, a French album, a Latin album, an Ella Fitzgerald and Louis Armstrong duet record made with the trumpeter Byron Stripling. Most of the Venus titles were sold only in Japan, which is why in 2013 she and her husband Brian Wittman set up their own label, Ooroo Records, and licensed fourteen remastered Venus tracks from the label's founder Tetsuo Hara as The Best Of Venus Volume One. The Arbors run went in parallel and stayed American: three trio albums with Sportiello and the drummer Eddie Metz Jr., a two-singer date with Rebecca Kilgore, tributes to Blossom Dearie and to the songs of the 1960s and 1970s, and a working band that has repeatedly included Harry Allen on tenor and John Di Martino on piano. She also turns up on other people's dates from the same circle, among them Chuck Redd's Groove City and Allen's For George, Cole and Duke, recorded in 2014 with Ehud Asherie at the piano and Redd producing, and released in April 2015. One date from these years sits outside the Arbors and Venus worlds entirely: the guitarist Gene Ess wrote A Thousand Summers (SIMP Records, 2012) as a set of ten standards arranged specifically for her voice, and she sings on it without playing at all.

She married Brian Wittman, her photographer, co-manager and occasional lyricist, on August 16, 2014, at their farmhouse in Brookfield, Connecticut. Then, after almost three decades in the New York scene and with the pandemic having removed every gig at once, the two of them bought a house in northern New South Wales and left the United States on May 1, 2021. The move is audible in the records. Great 70's, taped at Trading 8's Studio in New York on December 28 and 29, 2020, is the last New York session; Misty was made at Queensland University in November 2022 with an Australian band, and After Midnight, her most recent album, was cut in Brisbane in March 2025 and is a blues and rhythm-and-blues programme rather than a songbook. Feelin' Groovy (Arbors, 2024) was the first all-Australian band the label had ever recorded. She teaches weekly at Lindisfarne Anglican Grammar School in Tweed Heads, the northernmost town in New South Wales, co-leads a Northern Rivers band with the saxophonist Martha Baartz, and still tours: the Manly Jazz Festival in September 2025, a Japanese tour with the all-female Nippon Quartet in October, her first appearance at the Wangaratta Festival of Jazz and Blues in November, and the Perth Women's International Jazz Festival at the Ellington Jazz Club on June 27, 2026, her first Perth date in more than thirty years. She has also kept one American engagement, The Jazz Cruise, which brings her back most winters.

Parrott is one of a very small number of jazz musicians who work at professional level as both a bassist and a singer, and she is precise about why that is hard. The bass has to stay in time; a singer wants to lay a ballad back behind it, and the two demands pull against each other. She still practises with a metronome for that reason, has said that the bass sometimes has to go on autopilot so the lyric comes out in tune, and has increasingly solved the problem on ballads by putting the instrument down and just singing. Asked who else does the double, she named Esperanza Spalding, Katie Thiroux, Kristin Korb and Miriam Sullivan, and noted that audiences will always judge a voice more harshly than a bass line. Her bass playing was formed on transcriptions of Oscar Pettiford, Paul Chambers, Ron Carter and above all Ray Brown, and the lesson she says she actually learned from Brown was about sound rather than notes. As a singer she came to the work late and from the bandstand rather than the conservatory, which shows in an unforced, conversational delivery with the beat placed rather than pushed. Her chosen models are singers who picked their own material and were not interested in sounding like anyone else: Blossom Dearie, whose unapologetic feistiness she admires and whose Give Him The Ooh-La-La is her favourite record, and Peggy Lee, for the timing and the smoke in the sound. She has been candid about the risk in the tribute format, and about her husband stopping her mid-take on the Dearie album to tell her she was starting to mimic her subject. Les Paul's line about her, that she has a gift you cannot buy in a music store, is quoted on almost everything she releases; JazzTimes has credited her with clear articulation, a sense of rhythmic assuredness and a touch of allure, and the Australian magazine Limelight called her a rarity, a first-class bassist whose playing is as sublime as her vocals. The guitarist Frank Vignola put the order the way a musician would: she is a great bassist, and she is beautiful too, but she is really a great bassist.