Kyle Clinton Eastwood was born on May 19, 1968, in Los Angeles, the son of the actor and director Clint Eastwood and Maggie Johnson, and grew up in Carmel, California. Jazz was the household soundtrack: his parents played records by Miles Davis, Dave Brubeck, Stan Getz, Ray Charles, Duke Ellington and Stan Kenton, and the first concert he remembers, at age nine, was the Monterey Jazz Festival, where he heard the Count Basie Orchestra led by Basie himself. Through his father he also met singers and players such as Ella Fitzgerald and Sarah Vaughan. Clint taught him the left-hand bass line of a boogie-woogie, piano lessons followed at six or seven, and he picked up a little guitar for his first credited film role in Honkytonk Man (1982). He turned seriously to bass in high school.

After a brief period studying film at the University of Southern California, he spent much of the 1980s and 1990s in Los Angeles playing electric and upright bass behind singers in rock bands at clubs such as the Whisky, the Roxy and the Troubadour, while studying jazz bass and theory with the fusion bassist Bunny Brunel in the mid to late 1980s. In the early 1990s he joined a jazz-fusion band at the Baked Potato, then led his own jazz quartet for several years. He had already begun working in his father's film world, co-writing the piece "Red Zone" with Michael Stevens for The Rookie (1990), and his official biography credits him with bass on Hans Zimmer's score for Regarding Henry (1991). A Kyle Eastwood Quartet took part in the 1996 Carnegie Hall tribute concert to Clint Eastwood's jazz connections, documented on Eastwood After Hours: Live at Carnegie Hall. A tape of standards and originals reached Steve Berkowitz at Sony, who offered him a record deal, and his debut as a leader, From There to Here, appeared on Columbia in 1998 with Larry Klein producing.

After several years in New York, Eastwood moved his family to France. By March 2015 he had lived in Paris for almost nine years, and in 2022 his own site still described Paris as one of his longtime home bases. He signed with the British label Candid in 2004 and then worked with Dave Koz's Rendezvous label, which issued Paris Blue (recorded in Paris with a studio cast including drummer Vinnie Colaiuta, saxophonist Doug Webb and trumpeter Jim Rotondi, with Clint Eastwood whistling on the opening track) and Now (2006), a looser set built around London players and songs by Ben Cullum. Metropolitain (2009), recorded at Studio Ferber in Paris and co-produced by Erin Davis and Stevens, brought in pianist Eric Legnini, trumpeter Till Brönner and drummer Manu Katché. In November 2010 he toured the United States with a band of Rotondi, saxophonist Jason Rigby, pianist Rick Germanson and Joe Strasser.

Alongside the albums he built a film-music career with Stevens. The pair contributed to Mystic River (2003), Million Dollar Baby (2004), Letters from Iwo Jima (2006), Gran Torino (2008) and Invictus (2009), and Eastwood also worked on the music for his sister Alison's Rails & Ties (2007), arranged music for Flags of Our Fathers and Changeling, and supplied pieces for J. Edgar (2011), in which he also appears on screen as a member of the Stork Club band. English Wikipedia counts nine of his father's films, and the Gran Torino theme was credited to Eastwood, his father, Stevens and the singer Jamie Cullum. His official biography lists an ASCAP award and a Golden Globe nomination.

His working band settled into a quintet of English players. Songs from the Chateau (Candid, 2011) was recorded at the fifteenth-century Château Couronneau in Ligueux, France, with pianist Andrew McCormack, saxophonist Graeme Blevins, trumpeter Graham Flowers and drummer Martyn Kaine. Beginning with The View from Here (recorded September 2012, released in Europe in March 2013) he moved to the French label Jazz Village, adding trumpeter Quentin Collins; Time Pieces followed in 2015 with Brandon Allen on tenor saxophone, and In Transit (recorded April 2017 in Malakoff, France) added drummer Chris Higginbottom, with the Italian saxophonist Stefano Di Battista as a special guest on four tracks. By 2017 the band was spending about three quarters of each year touring Europe, with a yearly trip to Asia and occasional American dates. Cinematic (November 8, 2019) recast film themes by Lalo Schifrin, Bernard Herrmann, John Williams, Michel Legrand, Henry Mancini, Ennio Morricone and others, and Eastwood Symphonic (September 1, 2023) set the quintet against the Czech National Symphony Orchestra, conducted by Gast Waltzing, in jazz arrangements of themes from Clint Eastwood's films. It reached number 7 on Billboard's Classical Crossover chart. As of November 2026 his official site lists quintet concerts in Carcassonne on November 6, at the Duc des Lombards in Paris on November 7 and 8, and in Burgos on November 9.

Eastwood has a big, rounded, woody tone on the double bass and moves easily between acoustic post-bop and the funkier electric playing of his earlier records; AllMusic places his sound on the line between straight-ahead and contemporary jazz. He describes the music he loves best as lyrical hard bop full of groove and sophisticated harmony, citing Art Blakey's Jazz Messengers with Lee Morgan and Wayne Shorter, Horace Silver's Blue Note records and Miles Davis's quintets of the 1960s, and he has named Paul Chambers, Ray Brown and Ron Carter as bassists he studied. Charles Mingus is a particular touchstone: the quintet's In Transit closes with an explosive reading of "Boogie Stop Shuffle," alongside arrangements of Thelonious Monk's "We See" and a Count Basie blues. His first decade on record ranged from electro-cool jazz (Paris Blue) to pop-flavored grooves (Now) and urban eclecticism (Metropolitain); from 2011 he committed to a stable acoustic quintet with a repertoire of originals by band members, standards and film themes, a taste he sums up with the line "cinema is my second passion." The albums have appeared on Billboard's jazz charts, from the Traditional Jazz list in 1998 to the Classical Crossover chart in 2023.