Rocco Scott LaFaro was born on April 3, 1936, in Newark, New Jersey, the son of a big band musician. When he was five his family moved to Geneva, in New York's Finger Lakes region. He started on piano in elementary school, switched to bass clarinet in middle school and played tenor saxophone in high school. He took up the double bass at 18, just before college, because a string instrument was required of music education majors. After three months at Ithaca College he concentrated on the bass, and he played in small groups at the College Spa and Joe's Restaurant on State Street in Ithaca.

From 1955 he was a member of trombonist Buddy Morrow's big band, and he is listed on Morrow's 1956 recordings for Mercury. He left Morrow to work in Los Angeles, where he spent most of his days practicing. He worked from sheet music written for clarinet to build facility in the upper register of the bass, and Red Mitchell taught him to pluck with the index and middle fingers independently. He worked with trumpeter Chet Baker, and in late 1957 he recorded in New York with the Pat Moran Trio, a session whose tracks were later reissued under LaFaro's own name.

His reputation grew in Los Angeles in 1958 and 1959. For much of 1958 he was in the band of pianist and vibraphonist Victor Feldman, with whom he made The Arrival of Victor Feldman in January 1958 and Latinsville! (sessions in December 1958 and March 1959). He also recorded with Hampton Hawes (For Real!, March 17, 1958), clarinetist Buddy DeFranco's septet, the Cal Tjader-Stan Getz sextet in San Francisco, and saxophonist Harold Land's quartet in Vancouver. In 1959 he was the bassist on arranger Marty Paich's album The Broadway Bit, alongside Art Pepper and Mel Lewis, and he worked with the Stan Kenton orchestra and clarinetist Benny Goodman. In New York in June 1959 he recorded with alto saxophonist Herb Geller's group, which included Thad Jones, Elvin Jones and, on separate days, Hank Jones and Billy Taylor.

Late in 1959 he returned east and joined Bill Evans, who had recently left the Miles Davis sextet, with drummer Paul Motian. The trio's first studio album, Portrait in Jazz, was recorded on December 28, 1959, and a second, Explorations, followed on February 2, 1961. Live recordings from Birdland in March, April and May 1960 document the trio between the two studio dates. Evans, LaFaro and Motian worked as three equal voices, with the bass answering and extending the pianist's lines in place of laying down a steady walking line, and often without anyone stating the time explicitly.

By late 1960 LaFaro was in demand well beyond Evans's trio. On December 19 and 20 he played on Jazz Abstractions, an Atlantic date supervised by John Lewis that paired Gunther Schuller's "Abstraction" and "Variants" with a piece by Jim Hall. On December 21 he took part in Ornette Coleman's Free Jazz, a double-quartet session with Coleman, Don Cherry, LaFaro and Billy Higgins in one stereo channel and Eric Dolphy, Freddie Hubbard, bassist Charlie Haden and drummer Ed Blackwell in the other. In January 1961 he replaced Haden in Coleman's quartet, and the two bassists had shared an apartment in Los Angeles. The quartet recorded Ornette! on January 31, 1961. Between jobs with Evans he also played in Stan Getz's band, recording with Getz in Chicago on February 21, 1961, and he received a greeting card from Miles Davis that suggested Davis wanted to hire him.

In June 1961 the Bill Evans Trio began two weeks at the Village Vanguard in New York. On Sunday, June 25, five sets were recorded, two in the afternoon and three in the evening. Evans and producer Orrin Keepnews chose the material for Sunday at the Village Vanguard to feature LaFaro, opening and closing the album with his two compositions, "Gloria's Step" and "Jade Visions"; further takes from the day became Waltz for Debby in 1962. In the days before his death he played with Getz at the Newport Jazz Festival. LaFaro was killed in a car accident on July 6, 1961, on U.S. Route 20 at Seneca, New York, between Geneva and Canandaigua, eleven days after the Vanguard recordings. He was 25. Evans did not perform for several months. According to Motian, a trio record date with Miles Davis had been arranged and was forgotten after the accident.

His own bass, made in 1825 in Concord, New Hampshire, by Abraham Prescott, was badly damaged in the crash and later restored; Marc Johnson, Evans's last regular bassist, played it on a 2008 Evans tribute album by Eliane Elias. Two posthumous releases carry LaFaro's name: Memories for Scotty (1988), which includes five tracks from a 1961 trio session with pianist Don Friedman and drummer Pete La Roca, and Resonance Records' Pieces of Jade (2009), which reissued those five tracks together with a 1960 rehearsal tape of LaFaro and Evans working on "My Foolish Heart". His sister Helene LaFaro-Fernandez published a biography, Jade Visions: The Life and Music of Scott LaFaro, with the University of North Texas Press in 2009, and in 2014 the city of Geneva made April 3 Scott LaFaro Day and renamed a downtown street Scott LaFaro Drive.

LaFaro changed what the double bass was asked to do in a rhythm section. Where bassists of his generation mostly supplied walking quarter notes, he played countermelodies against the piano, with a speed and accuracy in the upper register that his contemporaries could not match, and in the Evans trio the bass became a full partner rather than an accompanist. His preparation was relentless: Charlie Haden recalled him writing out Sonny Rollins solos in bass clef and practicing for hours, and Ray Brown said he was among the most talented young players he had heard and that the loss would set the instrument back about ten years. Bill Evans called him one of the most outstanding talents in jazz. Critic Joachim Berendt described his approach as an emancipation of the instrument, and Bass Player magazine ranked him number 16 on its list of the 100 greatest bass players of all time. His work spans the Los Angeles club and studio scene, the interactive trio playing of Evans and the free improvisation of Coleman.