Bernard Joseph Baron was born on June 26, 1955, in Richmond, Virginia, into a Jewish working-class family. He began teaching himself the drums at about age nine, learning by watching other players and listening to records, radio, and television. His early influences ran from the theme music of the television western The Wild Wild West and the guests on the Ed Sullivan Show to records by Art Blakey, Ray Charles, Booker T. and the M.G.'s, James Brown, the Beatles, and Jimi Hendrix. As a teenager he played in rock bands and Dixieland groups, and at 13 he got his first real gig when the regular drummer for a pianist named BJ Doyle fell ill and she decided within minutes that he should stay. After high school he spent a year at the Berklee College of Music in Boston.

Baron moved to Los Angeles in the early 1970s and began working professionally, playing with the singer Carmen McRae and with Al Jarreau, and freelancing with Chet Baker, Stan Getz, Dizzy Gillespie, and Hampton Hawes. AllMusic adds Art Pepper to the Los Angeles veterans he worked with. He is credited with percussion on McRae's live album At the Great American Music Hall (Blue Note, 1977), and Ronnie Scott's Presents Carmen McRae 'Live', also from 1977, lists him as well.

In 1982 he moved to New York City. His early New York credits include the Toshiko Akiyoshi trio album of 1983, pianist Enrico Pieranunzi's New Lands (1984), and Fred Hersch's Horizons (1985), and he also worked with trumpeter Red Rodney. He became a regular on the downtown scene around the Knitting Factory, co-leading the trio Miniature with saxophonist Tim Berne and cellist Hank Roberts (their first album, Miniature, was recorded in March 1988 for JMT) and recording with trumpeter Herb Robertson and with guitarist Pat Martino (The Return, 1987). Guitarist Bill Frisell became his closest long-term partner: All About Jazz says Baron was a member of the Bill Frisell Band for ten years until 1995, and their records together on the Frisell side begin with Lookout for Hope (ECM, 1988) and run through Before We Were Born, Is That You?, Where in the World?, Have a Little Faith, and the Buster Keaton film music of 1995.

The downtown scene also led to a long association with John Zorn. Baron was the drummer in Naked City, the band Zorn assembled in 1988 with Frisell, bassist Fred Frith, and keyboardist Wayne Horvitz, whose first album appeared on Elektra Nonesuch in February 1990. From 1993 he was the drummer in Zorn's Masada quartet with trumpeter Dave Douglas and bassist Greg Cohen, a group that played Zorn's Jewish-themed compositions in the lineup of Ornette Coleman's classic quartet; the DIW label issued ten studio albums from 1994, beginning with Alef, and Tzadik later issued live recordings and unreleased studio sessions. Baron also played in Zorn's Electric Masada, the Bar Kokhba Sextet, the Moonchild trio, The Dreamers, and the Nova Quartet, and AllMusic counts more than 50 recordings associated with Zorn. Outside that circle he recorded with singer Laurie Anderson (Strange Angels, 1989, and later albums) and contributed to David Bowie's Outside (1995); Bowie later praised how steady his time was.

As a leader, Baron first recorded with Barondown, a trio with tenor saxophonist Ellery Eskelin and trombonist Steve Swell. Tongue in Groove (JMT) was recorded live, with no mixing or editing, on May 1, 1991, and came out in 1992; RAIsedpleasuredot (New World) was recorded in February 1993; and Crackshot (Avant, with Zorn as executive producer) was recorded in August 1995. He then turned to song-based material with a band of alto saxophonist Arthur Blythe, Bill Frisell, and bassist Ron Carter, producer Lee Townsend overseeing Down Home (Intuition, 1997) and We'll Soon Find Out (1999), albums of his own compositions with a Southern, soul-jazz flavor. He followed them with Killer Joey (2000, self-produced, recorded at Tonic in New York with guitarists Steve Cardenas and Adam Levy and bassist Tony Scherr) and Beyond (2001), made with guitarist Elliott Sharp and the Italian guitarist Roberto Zorzi. Later leader releases are mostly duos and improvised meetings: Keys and Skins with pianist Antonello Salis (2008), Conversations with Jim Hall (2010), Just Listen with Frisell (recorded in Bonn in November 2008, issued in 2013), Live! with pianist Irène Schweizer (2017), and Now You Hear Me with percussionist Robyn Schulkowsky (2018).

Since 2000 Baron has been a steady presence on ECM, with the quartet of guitarist John Abercrombie (seven albums from Cat 'n' Mouse in 2002 to Up and Coming in 2017), the trio of pianist John Taylor and bassist Marc Johnson (Rosslyn, 2003, and Tramonto, 2025), pianist Steve Kuhn, bassist Gary Peacock, and guitarist Jakob Bro (Streams, 2016). He is the drummer on The Surrounding Green (ECM, 2025), a trio album with Fred Hersch and bassist Drew Gress, and in Sound Prints, the quintet of saxophonist Joe Lovano and Dave Douglas (Sound Prints: Live at Monterey Jazz Festival, 2015, and Scandal, 2018). A Dave Douglas quartet album with pianist Marta Warelis and bassist Nick Dunston, Four Freedoms, was released by Greenleaf Music on January 30, 2026, with Baron on drums.

AllMusic describes Baron as a drummer known for rhythmic imagination and musical empathy who bridges swinging post-bop and avant-garde experiment, and his working life bears that out: the same player is on a Carmen McRae club date, on John Zorn's hardcore-speed Naked City miniatures, and on the quiet ECM trios of Steve Kuhn and Gary Peacock. Reviewers of Tongue in Groove picked out the humor and noise of the band and his intense but tuneful drumming, and Jazziz heard his Southern roots in the soul-jazz writing of Down Home. David Bowie's praise for his steadiness points to the other half of the reputation, a drummer who can hold time exactly while the music around him changes character. Largely self-taught, he grew up on rock, television themes, and rhythm and blues as well as on records by Art Blakey, and his own compositions, written for the Barondown trio, the Down Home band, and Killer Joey, are compact and riff-based. He is also a sought-after duo partner, trading phrases on record with Bill Frisell, Jim Hall, Irène Schweizer, and Robyn Schulkowsky.