Dave Koz was born on March 27, 1963 in Encino, California. Koz attended William Howard Taft High School in Woodland Hills, California performing on saxophone as a member of the school jazz band. He later graduated from UCLA with a degree in mass communications in 1986, and only weeks after his graduation, decided to make a go of becoming a professional musician. Within weeks of that decision, he was recruited as a member of Bobby Caldwell's tour. For the rest of the 1980s, Koz served as a session musician in several bands, toured with Jeff Lorber. Koz was a member of Richard Marx's band and toured with Marx throughout the late 1980s and early 1990s. He also played in the house band of CBS' short-lived The Pat Sajak Show, with Tom Scott as bandleader.

In 1990, Koz decided to pursue a solo career, and began recording for Capitol Records. His albums there include Lucky Man, The Dance, and Saxophonic. Saxophonic was nominated for both a Grammy Award and an NAACP Image Award.

In 1994, Koz began hosting a syndicated radio program, The Dave Koz Radio Show (formerly Personal Notes), featuring the latest music and interviews with who's who in the genre. Dave co-hosted of The Dave Koz Morning Show With Pat Prescott on 94.7 The Wave, a smooth jazz station in Los Angeles for six years. He decided to leave the show in January 2007 and was replaced by Brian McKnight.

In 2002, Koz started a record label, Rendezvous Entertainment, with Frank Cody and Hyman Katz.

In an April 2004 interview with The Advocate, Koz came out publicly as a gay man. Later the same year, he was named by People magazine as one of their "50 Hottest Bachelors" in their June issue.

In 2006, Koz was selected to host a syndicated afternoon show for Broadcast Architecture's new Smooth Jazz Network. The show, based in Los Angeles, is broadcast on other Smooth Jazz stations across the country. Koz and Ramsey Lewis are the only two Smooth Jazz personalities to host two different syndicated shows during the week.

Capitol Records/EMI's "Forever Cool" (2007) features Koz in a new arrangement of "Just in Time" with the voice of the late Dean Martin.

Koz has promoted annual Dave Koz & Friends Jazz Cruises since 2005.

Koz is the host of a weekly half-hour television series named Frequency put on by Fast Focus. Koz interviews musicians on the show such as Earth, Wind & Fire, Jonathan Butler, and Kelly Sweet. At the end of each interview, he plays along with the musician, adding some of his saxophone riffs to one of their hit songs.

Koz was also the bandleader on The Emeril Lagasse Show. The band, Dave Koz & The Kozmos, featured Jeff Golub (guitar), Philippe Saisse (keyboards), Conrad Korsch (bass guitar), and Skoota Warner (drums).

Koz plays a Yamaha silver alto sax (YAS-62S) with a No. 7 Beechler metal mouthpiece, a Yamaha straight silver Soprano sax (YSS-62S) or a vintage Conn curved soprano sax with a No. 8 Couf mouthpiece, and a Selmer Mark 6 Tenor sax with a Berg-Larsen 90/2 hard rubber mouthpiece. As for reeds, he uses size 3 Rico Plasticover.

On September 22, 2009, Koz received a star on the Hollywood Walk of Fame.

In October 2010, Koz performed "Start All Over Again" in a Desperate Housewives season 7 episode "Let Me Entertain You", alongside singer Dana Glover.