Matt Penman was born in 1974 in Palmerston North, on New Zealand's North Island, and took his first music lessons at home: classical piano from his mother, a piano teacher. He came to the bass at fourteen and grew up playing in Auckland, where there was no school teaching contemporary music at the time and the whole education happened on the bandstand. He played funk, rock and pop gigs alongside the jazz ones, an experience he has credited for the groove orientation that still shows in his time feel, and he learned the repertoire from records that were scarce enough in New Zealand to be worn out one at a time. Ray Brown and Ron Carter came first, then Gary Peacock, Dave Holland, Marc Johnson, Charlie Haden and Eddie Gomez, with Paul Chambers arriving late and on someone else's recommendation. Because he was gigging on electric bass at the same time, Jaco Pastorius, Stanley Clarke and Marcus Miller counted just as much.

He belonged to a small circle of Auckland players, informally the Young Lions, that also held the pianist Mark de Clive-Lowe, the saxophonist Jason Jones and the guitarist Greg Tuohey. The group made an album, Urbanism, partly to raise money to study abroad; it was nominated for New Zealand Jazz Album of the Year in 1994, and in 1996 Penman received a TVNZ Young Achiever award on the strength of it and of his live work. A cassette tape he mailed to the Berklee College of Music won him a scholarship, and he moved to the United States in 1994, studying with Herb Pomeroy and Hal Crook. He left after about nine months, by his own account too impatient to stay, and arrived in New York at the end of 1995 at twenty. The first years were lean. He played whatever club would pass a hat, sometimes for eight or nine dollars a night, and stayed solvent partly on European touring built from contacts made in Boston.

His first record under his own name came quickly. Flipside (Naxos Jazz, 1998) was cut live to two-track at Systems Two in Brooklyn on December 10 and 11, 1997, co-billed to Penman, Greg Tuohey, Jérôme Sabbagh and Darren Beckett, with four of its eight pieces his and the New Zealand pianist Mike Nock as executive producer. Around it he became a fixture of Jordi Pujol's Barcelona label Fresh Sound New Talent, where the New York musicians of his generation were recording: Chris Cheek's Vine, recorded December 20 and 21, 1999, put him in a quintet with Brad Mehldau, Kurt Rosenwinkel and Jorge Rossy. In November 2000 he went to Cologne to record with the trombonist Nils Wogram, Hayden Chisholm and the drummer Jochen Rückert; the piano-less quartet they named Root 70 has now produced ten albums across twenty-two years and is the longest-running band of his career. His own The Unquiet (Fresh Sound New Talent, recorded December 5 and 6, 2001) used Cheek, Rosenwinkel, Aaron Goldberg and Jeff Ballard and was written entirely by him.

In 2005 he took over the bass chair of the SFJAZZ Collective, the eight-piece composers' band founded in San Francisco the year before, succeeding Robert Hurst. He held it for thirteen seasons, through 2017, longer than any other member of the rhythm section, and was replaced by Matt Brewer in an announcement dated May 5, 2018. Each season the Collective built a book from one composer's work plus a new original from every member, and the annual live albums document Penman's writing alongside his playing from the second season on, when "Sega Games" appeared next to arrangements of John Coltrane. Over those years the group worked through Thelonious Monk, Wayne Shorter, McCoy Tyner, Horace Silver, Stevie Wonder, Chick Corea, Joe Henderson and Miles Davis, and its bandstand put him beside Bobby Hutcherson, Nicholas Payton, Mark Turner, Miguel Zenón, Renee Rosnes, Stefon Harris, Robin Eubanks, Edward Simon and Warren Wolf.

New York work ran continuously underneath all of it. He was the bassist in Ari Hoenig's quartet with Jean-Michel Pilc and Jacques Schwarz-Bart that made The Painter, recorded live and in closed session at Fat Cat on September 12 and 13, 2003; the SmallsLIVE archive logs 199 sets by him at Smalls and Mezzrow between October 1, 2007 and dates booked into late 2026. His second leader album, Catch of the Day (Fresh Sound New Talent, recorded April 8 and 9, 2007), introduced the band that shaped the next decade: Aaron Parks on piano, Eric Harland on drums and Seamus Blake on saxophones. Penman and Harland then played nine of the ten tracks of Parks's Blue Note debut Invisible Cinema, cut in January and March 2008.

That chemistry became a band. In 2009 Joshua Redman brought the three of them together at the Montreal Jazz Festival as James Farm, a cooperative quartet in which every member wrote and every arrangement was decided collectively. Its Nonesuch debut, recorded August 26 to 29, 2010 at the Clubhouse in Rhinebeck, New York and released in April 2011, opens with Penman's "Coax" and closes with his "Low Fives," with "1981" his third contribution; City Folk, recorded January 4 to 7, 2014 in Brooklyn, again carries three of his pieces. He is also the bassist on four of the seven tracks of Redman's Trios Live, the ones taped at the Jazz Standard in October 2009, and he co-arranged the Led Zeppelin closer "The Ocean" with Redman.

Since then he has recorded a third leader album, Good Question (Sunnyside, 2018), and settled into a set of long partnerships: the Aaron Goldberg trio with Leon Parker that began with At the Edge of the World (2018), Root 70, and a run of co-led piano and guitar trios including Not the Same River with Tomer Cohen and Obed Calvaire (2023), Heartbeat with Ben Winkelman and Gilad Hekselman (2023) and Aloft with Bryn Roberts and Quincy Davis (2024). Billy Childs's Triumvirate (Mack Avenue, 2026) puts him in a piano trio with Hoenig. He teaches as well as plays: workshops across Europe, a residency at the Brubeck Institute in Stockton, California, the faculty of the 2009 Banff Workshop for Creative and Improvised Music, and a place on the faculty of the Roots, Jazz and American Music program at the San Francisco Conservatory of Music.

Penman is a bassist whose reputation rests on time and sound rather than on virtuoso display, and the players he cites explain the priorities: Ray Brown and Ron Carter for weight and placement, Charlie Haden and Gary Peacock for the freedom to leave a line unfinished, and a parallel electric-bass education under Jaco Pastorius and Marcus Miller that left him hearing acoustic and electric as one instrument. He has described what he shares with Eric Harland as feeling the beat in the same place, and the two of them function in James Farm as a groove foundation that can move anywhere without losing the pulse. As a composer he writes song-shaped pieces with clear melodies and a rhythmic hook rather than harmonic obstacle courses, which is why the same writing works in a cooperative quartet, in the SFJAZZ Collective's eight-piece book, and on his own trio and quintet records. Critics have consistently reached for the low end when describing him: All About Jazz wrote that he brought out the bottom of the music in a way bassists rarely conceive, and reviewers of Good Question singled out the moments where he takes the lead voice, calling the record unfailingly pretty without that being a criticism, because the writing carries enough intellectual weight to survive the description.