Dan Siegel was born in Seattle, Washington, in 1954 and grew up in Eugene, Oregon. He started piano lessons at eight and by twelve was fronting a rock band, playing guitar and performing for pay. He studied composition at the University of Oregon and attended the Berklee College of Music in Boston before turning to his own recordings.

Inner City Records, a well-known independent jazz label, signed him in 1979. His debut Nite Ride (1980) carried guitar solos by Lee Ritenour on two tracks and a tenor saxophone appearance by John Klemmer on one. The second Inner City album, The Hot Shot, reached the top ten of Billboard's jazz albums chart, and Oasis followed in 1981, including a Donny Hathaway composition. Elektra released a self-titled album in 1982 with Tom Scott on saxophone and Larry Carlton, Abraham Laboriel, John Robinson and Lenny Castro among the players. From the start he mixed jazz with synthesizers, pop melody, funk and film-style writing, a blend Wikipedia describes as new age in the early records and contemporary jazz in the later ones.

He settled in Los Angeles in the early 1980s and recorded for Pausa. Another Time, Another Place (1984), made with bassist and synthesist Patrick O'Hearn and percussionist Alex Acuña, is the record AllMusic singles out as a pioneering blend of jazz-funk and electronics, later sampled by hip-hop and electronic dance producers. Reflections (1983) and On the Edge (1985) sit on either side of it, and On the Edge adds Tom Scott and guitarist Carl Verheyen. In the same years he became a screen composer. He scored the films Reform School Girls and Happy Hour (both 1986) and the television series Hard Copy (1987), supplied the forecast music for The Weather Channel's Local Forecast segments from 1986 to 1991, served as musical director and conductor of CBS's late-night show Overtime with Pat O'Brien in 1990, and played on the soundtrack of The Usual Suspects.

His 1986 Epic debut Short Stories began a steady move from fusion toward the contemporary, or smooth, jazz format. That year he also formed Birds of a Feather, a studio band of Los Angeles players that included Alex Acuña, saxophonist Richard Elliot, guitarist Carl Verheyen, drummer John Robinson and bassist Neil Stubenhaus. Siegel wrote and produced its three albums, issued in 1987, 1994 and 1997. Northern Nights (1987) became a reference point for the contemporary jazz that followed, and Late One Night (1989) featured the band's members. Going Home (1991, Epic) brought in singer Kenny Rankin and, for the first time, the influence of South African township music and Brazilian rhythm. The Getaway (1993) was a small-group jazz-funk record, Hemispheres (1995) wove Caribbean, Latin, West African and Brazilian rhythms into his playing, and Clairvoyance (1998) leaned toward urban-flavored jazz-pop. Epic and Legacy issued the career compilation Along the Way in 2000.

In the 2000s he moved to the Southern California label Native Language Music. Inside Out (2004) reunited him with drummer Oscar Seaton and returned to funky, radio-ready contemporary jazz, and Departure (2006) was played on acoustic piano with Brian Bromberg co-producing. Fables (2008) was billed to the Dan Siegel Project. Sphere (2009), with saxophonists Tom Scott and Gary Meek among the guests, was the first release on his own Dan Siegel Music imprint. Indigo (2014) pairs contemporary jazz with a post-bop edge, and its title track spent more than twenty weeks in the top twenty of the smooth jazz songs chart. Origins followed in 2018. Faraway Place (2021) was built during the pandemic: drummers Vinnie Colaiuta and Steve Gadd were recorded at East West Studios in Los Angeles, and Siegel, working from their files, added the piano and accordion afterward while a list of players including Eric Marienthal sent in their parts remotely.

Unity (2024) is a groove-centered trio record with drummer Oscar Seaton, bassist David Ginyard and a horn section led by Tom Scott, with six guitarists across the tracks; in its liner notes Siegel describes it as his 23rd album and reflects that at 70 he may be entering the final chapter of his career. He kept working. Resolution, a nine-song album produced by Siegel with Brian Bromberg on bass and Jay Bellerose on drums, was recorded between January and April 2026 and released that year, with a dedication to his mother, Elizabeth Siegel (1929 to 2026), who pushed him toward music. As of November 2026 he is alive and still recording.

Siegel is a smooth jazz and contemporary jazz pianist and keyboardist, and his catalog has to be read in that light. The earliest records, issued on Inner City and Pausa, sit close to new age and electronic music, built on synthesizer textures and long melodic lines, and Wikipedia classes them that way. From Short Stories onward he worked squarely in the contemporary jazz format of radio airplay and major-label singles, while keeping a funk pulse and an interest in African, Brazilian, Caribbean and Latin rhythm. Writing for film and television is a second thread: his tunes are built around short, singable themes, a screen composer's habit. The later records, including Indigo, Sphere and Unity, drop most of the synthetic gloss for acoustic piano, Fender Rhodes and organ, working with players from the Los Angeles studio and jazz-fusion community, among them Brian Bromberg, Lenny Castro and guitarist Allen Hinds. His peers and collaborators come from fusion and smooth jazz rather than the bebop line, with Lee Ritenour and Tom Scott the best-known names who recur in his work.