Matt Brewer was born April 20, 1983, in Oklahoma City and grew up in Albuquerque, New Mexico, in a household built around music: both his father, Paul, and his grandfather were jazz musicians, and his mother was an avid music lover and radio DJ. He started on drums at three, working out rudiments on a small practice pad, but didn't take music seriously until he was ten, when a summer program at the Interlochen Center for the Arts put a bass in his hands. There he studied classical bass with Winston Budrow and Lawrence Hurst while his father handled the jazz side of his education at home.

The prodigy period that followed was unusually fast-moving. Brewer began gigging professionally around Albuquerque at twelve and, while still in middle school, twice won the highest award at a regional music festival — an honor that, by multiple accounts, had never before gone to a student that young. He went on to study with Jean-Luc Matton, then principal bassist of the New Mexico Symphony, before enrolling at Interlochen Arts Academy. In his junior and senior years there, he was selected for the Grammy Band and performed on the 2000 Grammy Awards telecast — the first group ever to appear on the broadcast without being a nominee, putting a sixteen-year-old Brewer on national television years before his professional career formally began.

After Interlochen, Brewer entered the inaugural class of the Juilliard Jazz Program, studying with bassists Rodney Whitaker and Ben Wolfe. He left after two years, not from any falling-out with the school but because the touring work was already outpacing a conservatory schedule. He moved to New York in 2001, and within a few years was working with Greg Osby, Gonzalo Rubalcaba, drummer Jeff "Tain" Watts, guitarist Vic Juris, and guitarist Adam Rogers — the start of a sideman career that would come to define him as one of the most in-demand bassists on the New York scene. He appears on Osby's Channel Three (2005, Blue Note), a quartet date with Watts on drums, and on Rubalcaba's Avatar (2008, Blue Note), alongside drummer Marcus Gilmore, saxophonist Yosvany Terry, and trumpeter Michael Rodriguez. He has also toured with Steve Coleman and worked extensively in Ambrose Akinmusire's circle, including dates in Akinmusire's quartet alongside pianist Sullivan Fortner and drummer Justin Brown, with Kurt Rosenwinkel sitting in as a guest on at least one such performance.

Brewer's discography as a sideman runs deep and wide rather than narrow. He is a longtime member of alto saxophonist Steve Lehman's trio with drummer Damion Reid, a partnership that spans Dialect Fluorescent (2012, Pi Recordings), Dual Identity (2010, Clean Feed, co-led with Rudresh Mahanthappa), The People I Love (2019, Pi Recordings, with Craig Taborn), and a 2025 live tribute to Anthony Braxton recorded with Mark Turner added to the group. He has been a regular in trumpeter Alex Sipiagin's Criss Cross dates (Balance 38-58, 2015; Moments Captured, 2017; Mel's Vision, 2023, the latter two alongside saxophonist Chris Potter), in drummer Antonio Sánchez's band Migration (The Meridian Suite, 2015; Lines in the Sand, 2018), and in guitarist Mike Moreno's working group (First in Mind, 2011; Another Way, 2012). Other studio credits include David Binney's Anacapa (2014), Ben Wendel's The Seasons (2018), Tigran Hamasyan's standards album StandArt (2022, alongside Ambrose Akinmusire and Mark Turner), Ben Monder's Day After Day (2019), Tyshawn Sorey's trio album Mesmerism (2022), and saxophonist Tineke Postma's Freya (2020), on which he plays alongside Ralph Alessi, Kris Davis, and Dan Weiss. He has also been a longstanding member of the SFJazz Collective, appearing on the group's recordings and live releases across multiple seasons, and playing on albums by John Escreet, Lage Lund, Will Vinson, and Yaron Herman, among many others.

As a leader, Brewer has released three albums on the venerable Dutch-American label Criss Cross Jazz. His 2014 debut, Mythology, fronts a sextet with Steve Lehman and Mark Turner on saxophones, Lage Lund on guitar, David Virelles on piano, and Marcus Gilmore on drums, playing seven Brewer originals plus an Ornette Coleman tune. Unspoken (2016) pares down to a quintet with Ben Wendel, Aaron Parks, Charles Altura, and Tyshawn Sorey. Ganymede (2019), his first trio record, features tenor saxophonist Mark Shim and drummer Damion Reid across a mix of originals and repertoire by Ron Carter, Joe Henderson, Ornette Coleman, and Dewey Redman; DownBeat's review of the album stated flatly that "Matt Brewer will swing your head off your shoulders." He has also co-led less conventional projects: the guitar trio NY3 with Romain Pilon and Colin Stranahan (2012), The Colour of Intention with vibraphonist Lewis Wright and Marcus Gilmore (2020, Signum Classics), and, alongside pianist Aaron Parks and drummer Eric Harland, the self-released Volume One and Volume Two (2022). More recently he has been part of Out Of / Into, contributing production work to that group's Motion releases (2024-2025).

The Jazz Gallery commissioned Brewer for its 2012 Composers' Series, under the title "Leading From the Bass," pairing his original compositions with saxophonists Steve Lehman and Kyle Wilson, guitarist Mike Moreno, pianist David Virelles, and drummer Craig Weinrib. He placed third in the 2009 Thelonious Monk International Jazz Bass Competition. Beyond performing, Brewer teaches as adjunct faculty at The New School, leads masterclasses internationally, and has taught at Centrum's Jazz Port Townsend program, where he appeared in the John Clayton Bass Septet at the July 2024 festival.

Brewer's playing sits at the intersection of two jazz vocabularies that don't always overlap: the harmonically rigorous, "inside" postbop tradition of players like Ron Carter, and the more abstract, spectral-harmony language associated with Steve Lehman and the AACM lineage Lehman draws from. That range is exactly what his own records showcase — Ganymede deliberately alternates standard-repertoire "inside" playing against "outside" material by Ornette Coleman and Dewey Redman, and reviewers of his 2014 debut Mythology singled out an "adventurous, lyrical bent as a composer" beneath the technical command. As a sideman, that same adaptability is what has kept him in such different rooms: the microtonal precision Lehman's trio demands, the straight-ahead swing of Sipiagin's Criss Cross dates, the knotty through-composed structures of Antonio Sánchez's Migration, and the freer, rhythmically elastic language of Ambrose Akinmusire's and Tyshawn Sorey's working groups. Composition runs through his leader output as much as playing does — each of his three Criss Cross albums is built primarily around his own writing, filled out with carefully chosen covers that signal where his ear sits stylistically at that moment.