Thomas Wright Scott was born in Los Angeles on May 19, 1948, into the film-scoring business rather than the jazz club circuit. His father, Nathan Scott, was a composer for film and television with more than 850 credits, among them Dragnet and Lassie. Scott led a group called the Neoteric Trio as a teenager and was working professional Los Angeles sessions before he finished school, including big-band dates with the Don Ellis Orchestra and Oliver Nelson's big band.

His first album as a leader, The Honeysuckle Breeze, was recorded on September 18, 19 and 20, 1967, when he was 19, and released on Impulse!. Bob Thiele produced, Rudy Van Gelder cut the lacquer, and Ralph J. Gleason wrote the liner notes. Carol Kaye and Max Bennett played Fender bass and Glen Campbell played guitar. The program set John Coltrane's "Naima" alongside Donovan's "Mellow Yellow," which established early the position Scott held for the rest of his career: a jazz improviser entirely comfortable inside popular material. Rural Still Life followed on the same label in 1968. Quincy Jones, watching him around this time, said "he's 21, and out of sight!"

In 1973 Scott formed the L.A. Express, a band that turned out to be one of the connective structures of 1970s crossover jazz. The original lineup was Larry Carlton on guitar, Joe Sample on keyboards, Max Bennett on bass and John Guerin on drums, with Carlton and Sample simultaneously members of the Crusaders. The band's first work outside Scott's own records was backing Joni Mitchell on Court and Spark, released in January 1974, and on the live double album Miles of Aisles later that year, where they were billed on the sleeve alongside her.

The following eighteen months compressed most of the crossover argument into one stretch of calendar. In April 1974 George Harrison heard the L.A. Express at a Mitchell show in London and brought the group to Friar Park to cut basic tracks for Dark Horse; Scott went on to play Harrison's North American tour that autumn. At the 17th Grammy Awards in March 1975, Scott and Mitchell won Best Arrangement Accompanying Vocalist(s) for "Down to You." On July 19, 1975, Wings' "Listen to What the Man Said" reached No. 1 on the Billboard Hot 100 carrying Scott's soprano saxophone solo, which was kept from the first take after Paul McCartney had spent weeks dissatisfied with the track. That same year Scott's composition "Gotcha" became the theme to Starsky & Hutch, and Tom Cat, credited to Tom Scott & the L.A. Express, was nominated for Best Pop Instrumental Performance at the 1976 ceremony.

New York Connection, recorded at the Hit Factory between August 25 and 29, 1975, moved him into the East Coast session world. The band was Bob James on electric piano, Steve Gadd on drums, Eric Gale and Hugh McCracken on guitar, Richard Tee on keyboards and Ralph MacDonald on percussion, with Harrison guesting on slide guitar. The album entered the Billboard 200 on December 20, 1975, charted for 25 weeks, and peaked at No. 42.

Through the later 1970s and 1980s Scott became one of the most heavily recorded session players in American popular music. He arranged and conducted the horn section on Steely Dan's Aja in 1977 and played saxes and flute on it. He played on Boz Scaggs' Silk Degrees, Carole King's Ode albums, Rod Stewart's Blondes Have More Fun, Blondie's Autoamerican, Toto IV, Whitney Houston's debut, and Pink Floyd's A Momentary Lapse of Reason, where he is credited on alto and soprano saxophone. He was a founding member of the Blues Brothers band, left after the 1980 tour in a dispute over pay, and returned in 1988.

His own records through this period kept solving the accessibility problem with technology instead of simplification. Scott played the Lyricon, an early electronic wind instrument, on Tom Cat (1975), Street Beat (1979), Apple Juice (1981) and Desire (1982), and he played the Lyricon solo on Captain & Tennille's No. 1 single "Do That to Me One More Time." He moved to the Yamaha WX-7 wind controller on Flashpoint (1988) and to the WX-11 with a VL-1 tone generator on Bluestreak (1996).

Apple Juice was recorded live at the Bottom Line in New York on January 15, 16 and 17, 1981, with Marcus Miller on bass, Gadd on drums, Gale and McCracken on guitar, Tee on keyboards, MacDonald on percussion and Dr. John guesting. A long run on GRP began with Streamlines in 1987 and continued through Flashpoint, Them Changes (1990, recorded with the house band from The Pat Sajak Show, which Scott led, and featuring a young Dave Koz), Keep This Love Alive, Born Again, Reed My Lips, Night Creatures and Bluestreak. The last of those reconvened Sample, Robben Ford, Gadd and MacDonald to re-record "Tom Cat," "Sneakin' in the Back" and other Ode-era material twenty years on.

Scott conducted the GRP All-Star Big Band to a Grammy for Best Large Jazz Ensemble Performance for All Blues at the 38th ceremony in 1996, the same year he served as music director for the 68th Academy Awards. He has also been music director on Emmy Awards telecasts, and received an Emmy nomination in 2017 for musical direction on the Tony Bennett 90th birthday special. He composed the themes to The Streets of San Francisco and, with Johnny Mathis, Family Ties, and scored Conquest of the Planet of the Apes.

He continues to record. In August 2025 he appeared on Live at Vic's Las Vegas, co-billed with vocalist Nicole Zuraitis and drummer Dan Pugach, recorded over three nights at Vic's in Las Vegas that June with Keyon Harrold on trumpet, Rachel Eckroth on organ, Idan Morim on guitar and Sam Weber on bass. The album was nominated for Best Jazz Vocal Album at the 68th Grammy Awards. The span between his first session as a leader in September 1967 and that June 2025 date is 58 years. He turned 78 in May 2026.

Scott's playing is rooted in the West Coast studio tradition he was raised inside: a big, centered tone, clean articulation, and a sight-reading fluency that made him first call for arrangers who needed a soloist who could also lead a section. He plays tenor, alto and soprano saxophone and flute, and his soprano work in particular is what most listeners have heard without knowing it, because it carried the hooks on records made for radio.

What distinguishes him from the smooth-jazz players he is often shelved beside is the direction of the compromise. Scott's commercial exposure came from sideman work on other artists' hit records, not from softening his own. The albums under his name stayed as harmonically and rhythmically involved as he wanted them to be, because they never had to carry the singles. When he reached for accessibility on his own records, he reached for new instruments rather than simpler lines, which is why the Lyricon and the Yamaha wind controllers recur across four decades of his catalog.

As a bandleader his instinct was to hire players who were already leaders themselves. The first L.A. Express contained two working Crusaders, and the 1996 reunion on Bluestreak pulled back Joe Sample, Robben Ford, Steve Gadd and Ralph MacDonald. As an arranger he worked in the same register, most visibly on Aja, where the horn writing has to sit inside an unusually precise production without flattening it.