David Richard Matthews was born on March 4, 1942, in Sonora, Kentucky, a town of a few hundred people. His father was a Methodist minister, so the family moved often, and he went to high school in Louisville. His mother played piano. He was born with an underdeveloped right side and plays chords with the fused fingers of his right hand, moving the hand the way a vibraphonist handles four mallets. He took trumpet lessons for a short time, found French horn a better fit, and taught himself piano. Chet Baker and Dave Brubeck records at the end of the 1950s pulled him toward jazz.

In 1960 he enrolled at the College-Conservatory of Music in Cincinnati, studying classical composition as a way to become a better improviser, and graduated with a bachelor's degree in composition. He led a college big band and paid his tuition with club work. From 1966 to early 1968 he lived in Europe with a six-piece band that worked American military bases in Germany and Italy, then returned to Cincinnati and played six nights a week with a jazz group called the Sound Museum.

Cincinnati was the home of King Records, and a production coordinator for James Brown heard the band. When a studio booking for it fell through, Brown asked for an arranger, and Matthews wrote six charts that Brown first found too straight. An engineer persuaded Brown to listen to the hip passage, and he got the job. By his own account the first of his arrangements to be released was "Any Day Now," on the album It's a Mother. From 1970 he was an arranger and bandleader for Brown's organization, a freelancer rather than a salaried employee, and after Pee Wee Ellis left Brown's band he became the main arranger. Brown's People label also issued Matthews's own first record, The Grodeck Whipperjenny (People PS-3000, 1971), a psychedelic funk album he produced with Ron Lenhoff at the Starday-King studio in Cincinnati, with Matthews on piano, organ and trombone, Michael Moore on bass, Jimmy Madison on drums and Kenny Poole on guitar. He moved to New York in 1971 and worked as a freelance arranger on albums, commercials and film scores, for clients that included Buddy Rich, the singer Mark Murphy, Bonnie Raitt and the Starland Vocal Band, and a 3M Tape commercial won him a Clio Award in 1975. He arranged Blue Mitchell's Many Shades of Blue (Mainstream, 1974) and wrote the charts for Everything I Do Gonna Be Funky by the guitarist O'Donel Levy.

The turning point was 1975, when Creed Taylor hired him to arrange a Ron Carter album for the Kudu label, Anything Goes. He stayed as CTI and Kudu's staff arranger until 1978 and became one of the people who defined the label's second half. His arrangements are on George Benson's In Concert: Carnegie Hall, Good King Bad and, with Joe Farrell, Benson & Farrell; on Hank Crawford's I Hear a Symphony, Hank Crawford's Back and Cajun Sunrise; on Esther Phillips's Capricorn Princess; on Grant Green's The Main Attraction; on Patti Austin's debut End of a Rainbow; on Grover Washington Jr.'s A Secret Place; on Art Farmer's Something You Got and Big Blues with Jim Hall; on Yusef Lateef's Autophysiopsychic; on Jeremy Steig's Firefly; and on Nina Simone's Baltimore (1978), where he also played piano. He produced and arranged two albums for the drummer Idris Muhammad, Turn This Mutha Out (1977) and Boogie to the Top (1978), which carried the disco-era hit "Could Heaven Ever Be Like This." Between those sessions he cut his own records, beginning with a live big-band date at the Five Spot in New York on May 26 and June 2, 1975 (Muse), then Shoogie Wanna Boogie (Kudu, 1976), a studio big-band record, Night Flight (Muse, 1977), and Dune (CTI, 1977).

Dune was Taylor's concept, tied to Frank Herbert's novel and packaged to echo Star Wars. Side one is a suite of Matthews originals ("Arrakis," "Sandworms," "Song of the Bene Gesserit," "Muad'dib"), and side two is arranged space-themed covers: David Bowie's "Space Oddity," the theme from Silent Running, and two John Williams Star Wars themes. Grover Washington Jr., David Sanborn, Steve Gadd, Eric Gale and Hiram Bullock are among the players. Hip-hop producers later kept finding the record: his music has been sampled by the Notorious B.I.G., Nas, MF DOOM, Method Man, Redman and Large Professor, and DOOM's "Rapp Snitch Knishes" samples the "Space Oddity" cover. Matthews also orchestrated film scores in these years, including The Stepford Wives and Night Moves (both 1975), and wrote music for William Greaves's The Fight and for Stony Island (1978).

CTI's finances were failing by 1978, and Matthews's career turned toward Japan. From 1979 to 1989 he was an artist, producer and writer for King Records of Japan, recording for its Electric Bird label with the Electric Birds (Digital Love, 1979, and Cosmic City, 1980), the First Calls and other studio groups. He also arranged and conducted the orchestra on Earl Klugh's Heart String (1979) and on two tracks of Klugh's Wishful Thinking (1984). In 1983, at the suggestion of the magazine Swing Journal and King, he formed the Manhattan Jazz Quintet with trumpeter Lew Soloff, tenor saxophonist George Young and Steve Gadd on drums, with Charnett Moffett and then Eddie Gómez on bass. The first album was recorded on July 11, 1984, the group won Swing Journal's Gold Disk Award that year, and it has toured Japan almost every year since, with the American jazz audience seeing it only rarely. The rhythm section changed over time: Gadd left after 1987, Dave Weckl and bassist John Patitucci played on the 1988 and 1989 albums, Peter Erskine on the early 1990s ones, and Victor Lewis and Moffett from 1993. Andy Snitzer had replaced Young on tenor by 2003, and the 2015 and 2017 albums feature trumpeter Michael Rodriguez and saxophonist Chris Hunter. In 1989 the quintet's book grew into the Manhattan Jazz Orchestra, a big band of New York players whose first album, Moanin', featured trumpeters Lew Soloff, Randy Brecker and Jon Faddis and trombonists Jim Pugh and Urbie Green, with Ryan Kisor and Scott Robinson among its later soloists. From February 1990 Matthews was under an exclusive contract to the Tokyo company Sweet Basil, which issued most of the groups' records through the decade. He and the producer Shigeyuki Kawashima received a Swing Journal critics' award in 1995 for the orchestra's Get It On. Milestone began releasing the orchestra's records in the United States in 2001, among them Back to Bach (issued in Japan as Bach 2000) and the Ellington tribute Hey Duke!, recorded in July 1999 and issued by Milestone in 2002.

The Japanese market kept him busy as a producer and arranger as well. He arranged Tatsuya Takahashi's big-band album Keeping Count (1986), conducted the strings on Mikio Masuda's Corazon (1979), produced the saxophonist Hidehiko Matsumoto's Papillon (1992) and Kisor's 2000 album Kisor, and wrote music for the animated series Yamato 2520 (1995 to 1996). He also led a funk project, J-Funk Express, whose Gettin' Back to My Roots (1993) has Maceo Parker on alto saxophone and Fred Wesley on trombone, two of Brown's former sidemen. Under his own name he recorded a long run of piano-trio and guest records, among them Tennessee Waltz with John Scofield, American Pie with Gary Burton and Concierto de Aranjuez with Jim Hall. His most recent leader record is Sir, (recorded March 3, 2018, and issued by Paddle Wheel in Japan and Birdland Records in the United States), a trio date with Eddie Gómez and Steve Gadd. He has lived in Japan since 2013, according to Japanese Wikipedia, which places him in Hachinohe, Aomori Prefecture, as of 2024.

Matthews comes from three places at once. The first is the big-band writing he learned in a conservatory and in Brown's band, where he transcribed a full Brown show and scored it for a 17-piece band. The second is the groove school of Brown's rhythm sections, which he carried into jazz as an arranger who knew exactly where the one falls. The third is the string-and-rhythm gloss of Creed Taylor's CTI studio, for which he wrote lush string and horn parts over a rhythm section of Eric Gale, Steve Gadd and their peers, work that jazz listeners at the time split over and that sample-based producers have since treated as a reservoir. AllMusic's biographer Eugene Chadbourne files him under post-bop, swing, funk and jazz-funk. In his own groups he writes more straight-ahead: the Manhattan Jazz Quintet plays hard-bop, standards and Latin tunes, and the Manhattan Jazz Orchestra plays Ellington, Basie, Glenn Miller and Bach. That split is why he sits in the crossover vault: a working jazz pianist and arranger whose career was made in R&B, disco, film and commercial work and in the Japanese market, which has absorbed far more of his output than the American one.