David Perry Hazeltine was born on October 27, 1958, in Milwaukee, Wisconsin. An older brother's jazz records were in the house, and when he was about ten or eleven his mother bought him Jimmy Smith's Plays the Standards, which made him a jazz listener and first pointed him at the organ. He began piano study at nine, took his first paid job at thirteen (a Friday-and-Saturday solo organ engagement at an Italian restaurant on Milwaukee's west side), and by about fifteen had settled on piano as his main instrument. Through high school he expected to become an electrical engineer, and he chose music school only shortly before college began. He attended the Wisconsin College Conservatory of Music from 1976 to 1979.

At twenty-one he became the house pianist at Milwaukee's Jazz Gallery, a club that booked touring soloists as singles and paired them with a local rhythm section. There he accompanied Sonny Stitt, Pepper Adams, Chet Baker, Charles McPherson, Al Cohn, Lou Donaldson and Eddie Harris. His first night with Stitt came with no rehearsal and a nervous hand, but the two became close, and he played many more dates with Stitt in the years before the saxophonist's death. Encouraged by Baker, Hazeltine moved to New York City in 1981; about two years later family considerations took him back to Milwaukee. He returned to the conservatory, where he was program coordinator of jazz studies and then chairman of the jazz department from 1985 to 1992, co-founded a local school called The Jazz School, and earned a BA from the University of Wisconsin in 1991.

In 1992 he moved back to New York, where he has worked since. His first regular work there was a small engagement at the Star Cafe on Seventh Avenue at 23rd Street with the tenor saxophonist Junior Cook, and he also played with trombonist Curtis Fuller and spent a period on the road with singer Jon Hendricks. He led a trio with bassist Peter Washington and drummer Louis Hayes and worked with the Carnegie Hall Jazz Band and with Slide Hampton's big band. His first album as a leader, 4 Flights Up (Sharp Nine, 1995), was recorded direct to two-track on July 27, 1995, at Van Gelder Studio in Englewood Cliffs, New Jersey, with Hampton on trombone, Washington on bass and Ray Appleton on drums. In the same decade he appeared on dates by Hayes (Louis at Large, recorded April 17, 1996), the alto saxophonist Jim Snidero and the tenor saxophonist Eric Alexander.

His best-known group is One for All, the hard-bop sextet of Alexander, trumpeter Jim Rotondi, trombonist Steve Davis, drummer Joe Farnsworth, Hazeltine and a bassist. Hazeltine and Washington began playing with the other four in 1996 at Augie's, the club later reopened as Smoke, and the band formed in 1997 for an engagement at Smalls Jazz Club in Greenwich Village. Its first album, Too Soon to Tell, was recorded for Sharp Nine on February 25, 1997. John Webber later replaced Washington on bass. The sextet's albums, seventeen through 2024, have appeared on Sharp Nine, Criss Cross, Venus, Jazz Legacy Productions, Cellar Live and Smoke Sessions, most recently Big George (2024), recorded on September 27, 2022, with the tenor saxophonist George Coleman as featured guest.

As a leader he has recorded most often in piano trios and in quartets with a tenor saxophonist. Between 1996 and 2002 he made three records as the Classic Trio with Washington and Hayes, the last of them with Alexander added. For Criss Cross he recorded How It Is (1998), Blues Quarters, Vol. 1 (sessions of December 1998, released 2000, with Alexander), A World for Her (1999), Good-Hearted People (2001), Close to You, Perambulation (2006), Blues Quarters, Vol. 2 (2007), Inversions (2010) and, most recently, Blues for Gerry (2023, with Washington and Farnsworth, recorded December 1, 2022). A run of trio albums for Venus in Japan began with Waltz for Debby (1999) and for much of it paired him with bassist George Mraz and drummer Billy Drummond; Hazeltine and Mraz also made Manhattan (Chesky, 2006), Your Story (Cube Metier, 2013) and Impromptu (Chesky, 2013), and, with Farnsworth, The New Classic Trio (2012). He co-led two quartet albums with the vibraphonist Joe Locke, Mutual Admiration Society (1999) and its 2009 sequel. I Remember Cedar (2014) honors the pianist Cedar Walton, who had died the year before; on The Time Is Now (Smoke Sessions, 2018) he played trio with Ron Carter and Al Foster, recorded on May 23, 2018, at Sear Sound in New York.

Beyond his own albums he has been a working sideman for decades: with James Moody on Homage (recorded May 21 to 23, 2003), with trumpeter Jon Faddis (a 2003 European tour and the 2006 album Teranga), with singer Marlena Shaw, with the British singer Georgie Fame on Poet in New York (2000), and on later records by Hayes, Alexander, Rotondi, Grant Stewart and Coleman. He has also taught: by 2003 he had been an associate professor at Berklee College of Music for a time and was otherwise teaching privately in his own studio. His current teaching commitments, if any, are not confirmed.

Hazeltine has said that saxophonists shaped him more than pianists: Charlie Parker, John Coltrane and Sonny Rollins are his main models, along with Joe Henderson, Cannonball Adderley and Eddie Harris, and he has described sitting down to learn and improvise in their styles. He prefers a horn's freedom and vocal phrasing to what the piano can do. Among pianists he credits Art Tatum for harmony and rubato ballad introductions, Barry Harris for flowing, swinging lines, Bill Evans for voicings and touch, McCoy Tyner for fourth voicings and rhythmic angularity, Herbie Hancock for musicality and harmony, Buddy Montgomery as a writer and phraser, and above all Cedar Walton for precisely articulated, Parker-like lines and elegant voicings. The result is a straight-ahead, hard-bop piano style built on melody and swing. He has said that composing does not come easily and that he is rarely satisfied with a tune until years after recording it, and that he values long-term musical partnerships because the music is communal. Walton himself praised Hazeltine's deep commitment to jazz history joined to current ideas. Critics have compared One for All to Blue Note-era hard bop and to Art Blakey's Jazz Messengers.