Chad Lefkowitz-Brown was born September 8, 1989, in Horseheads, New York, in the Southern Tier of the state, and grew up in the Elmira area. His father, a music teacher and multi-instrumentalist, started him on saxophone at nine and homeschooled him. The method books did not take; what did was improvising, and a stack of records his father put on that were heavy on saxophone players. Dexter Gordon's GO! was the album he later named as the one that turned him toward jazz. At eleven he began working around the Southern Tier with drummer George Reed, a local veteran who had backed Charlie Parker, Teddy Wilson, Buddy Tate, and Marian McPartland, and who mentored him for years. That same year he won the first of fifteen DownBeat Student Music Awards he collected before finishing school, in categories including Best Jazz Soloist and Best Original Song.

At eighteen he was selected for the Brubeck Institute Jazz Quintet at the University of the Pacific, the fellowship program Dave Brubeck founded, where he studied under pianist Joe Gilman and played with Brubeck at festivals in the United States and Canada. Two albums came out of that period on Capri Records under Gilman's name, Americanvas (2010) and Relativity (2012), plus the quintet's own 2009-2010 on the University of the Pacific's label. Moving to New York, he took a tenor chair in Arturo O'Farrill's Afro Latin Jazz Orchestra and appears on two Grammy-winning O'Farrill records: The Offense of the Drum (Motéma, 2014), which won Best Latin Jazz Album at the 57th Grammy Awards, and Familia: Tribute to Bebo + Chico (2017), a collaboration with Chucho Valdés whose "Three Revolutions" won Best Instrumental Composition. Sideman dates piled up quickly across the same years: guitarist Quentin Angus's Retrieval Structure, bassist Ron McClure's Ready or Not (SteepleChase, recorded January 2012 with violinist Gabe Terracciano, pianist Mike Eckroth, and drummer Shareef Taher), Clarence Penn's Monk: The Lost Files (Origin, 2014), Isaac Darche's Team & Variations (Challenge, 2014), and trumpeter Adam O'Farrill's Stranger Days (Sunnyside), cut at Avatar Studios on January 4, 2015.

His leader debut, Imagery Manifesto, came out in July 2013: all originals, with Adam O'Farrill on trumpet, Travis Reuter on guitar, Sam Harris on piano, Linda Oh on bass, and Kenneth Salters on drums. Critic Doug Ramsey named it debut album of the year. Reviewing it for Jazz Weekly, George W. Harris called the writing impressive and described the leader's tone as medium thick, modern, and metallic. Onward followed in May 2017, a quartet record with Raviv Markovitz on bass and Jimmy Macbride on drums, five Lefkowitz-Brown originals, three standards arranged by pianist Steven Feifke, and Randy Brecker guesting on "Franklin Street" and "Blues for Randy." Brecker became a regular touring partner across American and European festivals. In September 2018 Lefkowitz-Brown put out two very different records within three weeks: Electric Band: 2013-2014, drawn from earlier sessions, and Standard Sessions, a twelve-track run through the repertoire ("This I Dig of You," "Scrapple from the Apple," "Yardbird Suite," "What Is This Thing Called Love"). The electric side of his work got its own band the next year in Chad LB & Sonic Magic, with Ben Eunson on guitar, Noah Kellman and Feifke on keyboards, Tamir Shmerling on electric bass, and Shariq Tucker on drums, documented on a studio album and on Live at The Bridge, both 2019, with Lefkowitz-Brown doubling on electronic wind instrument.

The pandemic pushed him into large-ensemble writing. Quarantine Standards, released August 21, 2020 on Sound Frame Records, assembled eighteen musicians recording their parts separately at home, on eight new charts by Steven Feifke covering "Easy to Love," John Coltrane's "Giant Steps," Stevie Wonder's "Superstition," "Softly as in a Morning Sunrise," "Autumn Leaves," "Corcovado," and "Cherokee." "I've always wanted to do a big band album," he said at the time. "I don't know why, but something about being in quarantine and everybody being stuck at home without much work made me think this was the time." The follow-up went further. Open World (La Reserve Records, September 17, 2021) was credited to Chad Lefkowitz-Brown and the Global Big Band, a twenty-piece ensemble drawn from seventeen-plus countries and again recorded in isolation, then assembled, mixed, and mastered by Dave Darlington. The saxophone section put Eden Bareket on baritone alongside Makar Kashitsyn, Lucía Sarmiento, Shu Ishikawa, and Mina Nashaat, over a rhythm section of Holger Marjamaa, Russell Hall, Josh Meader, Keisel Jiménez, and the drummers Bryan Carter and Charles Goold. Nine guests soloed across the nine tracks: Arturo Sandoval, Randy Brecker, Andrea Motis, Miguel Zenón, Lionel Loueke, Melissa Aldana, Etienne Charles, Bria Skonberg, and Makoto Ozone. Between the two big-band projects came Quartet Sessions (La Reserve, February 19, 2021), an all-standards program from two dates: October 6, 2019 at 5th House in Brooklyn with Marjamaa, Dan Chmielinski, and Bryan Carter, and February 6, 2020 at 718 Studios with Feifke, Alexander Claffy, and Corey Fonville.

Alongside his own records he has held a chair in Chris Botti's touring band, and his pop and television credits include tours and broadcast appearances with Taylor Swift and Don Henley, an on-screen appearance in the 2021 film Here Today with Billy Crystal and Tiffany Haddish, and the tenor chair in Steven Feifke and Bijon Watson's Generation Gap Jazz Orchestra (Cellar Music, 2022), a band that also included Kurt Elling, John Fedchock, and Ulysses Owens Jr. He built a second career in education in parallel, founding the online publisher Jazz Lesson Videos and the Global Jazz Workshop, and joining the San Francisco Conservatory of Music as a visiting artist in its Roots, Jazz and American Music program. His recent output has moved toward a warmer, arrangement-led format: Time in a Bottle (April 4, 2025) sets his tenor against a string section on standards and pop material from "Autumn Leaves" to Jim Croce and Sting, followed by The Shadow of Your Smile (September 5, 2025), City Spirit (La Reserve, February 27, 2026), and Present Moments (La Reserve, August 7, 2026).

Lefkowitz-Brown calls himself a post-bop player, and the working format he keeps returning to is the one he grew up copying off records: tenor, piano, bass, and drums. "The four piece ensemble, and specifically the sax-piano-bass-drums format, is always special to me," he told JazzTrail. What reviewers pick out first is velocity and line construction, a dense chromatic vocabulary played clean at tempo, which is also what made him one of the first jazz musicians of his generation to build a large following through instructional video rather than club residencies. He credits the method books of Jerry Bergonzi and Walt Weiskopf as formative, and Dexter Gordon as the first player who made the music make sense to him. The New York Daily News called him a "sax phenom." His catalog splits fairly evenly between original post-bop writing (Imagery Manifesto, half of Onward) and standards played straight (Standard Sessions, Quartet Sessions), with an electric, EWI-and-effects side in Sonic Magic and a large-ensemble side that began as a lockdown workaround and has stayed part of what he does.