Morgan Guerin was born in 1998 in Metairie, a suburb just outside New Orleans, into a household built around music. His father, Roland Guerin, is a bassist who spent 1994 to 2009 in Marcus Roberts's band, 2008 to 2015 with Allen Toussaint, and later worked with Dr. John, and kept a home recording studio where he wrote, tracked and mixed his own records. Guerin gravitated to the drums as a toddler and had a kit of his own by age two; he added alto saxophone and the EWI around age six or seven, drawn to the instrument after hearing Michael Brecker's synthesizer-horn playing. Through his father's circle he was around members of the Marsalis family, drummer Herlin Riley, saxophonist Donald Harrison and pianist Allen Toussaint from an early age.

The family moved to Atlanta in 2009, where Guerin spent his teenage years absorbing the city's hip-hop and neo-soul alongside the jazz and R&B of his New Orleans childhood. He released his debut album, The Saga, in April 2016 at seventeen, playing tenor and alto saxophone, EWI, flute, piano, organ, keyboards, drums and percussion himself and writing every composition; the cover art traces a cartoon lineage from toddler drummer to teenage saxophonist as a visual account of how he got there. The Saga II followed in June 2017, and Guerin has described the two records, later joined by a third, as an "audio autobiography" tracking both his growing instrumental range and the artists shaping his writing, chief among them Wayne Shorter.

Guerin turned down a Berklee scholarship to study at the New School for Jazz and Contemporary Music in Manhattan, moving to New York in 2016 and later completing a master's degree; he has also studied at Berklee College of Music. In New York he became the electric bassist, saxophonist and later co-producer in drummer Terri Lyne Carrington's band Social Science, appearing on Waiting Game (Motéma, 2019) and returning as a full multi-instrumentalist and producer on Trip the Night Fantastic (Candid, 2026), where he plays bass, saxophone, EWI, organ, keyboards, percussion and drums across every track and both produced and mixed the record. The same year he was also the additional producer, electric bassist, synth player and backing vocalist on Esperanza Spalding's Grammy-nominated 12 Little Spells (Concord Records, 2019), sharing a composing credit on one track. He completed The Saga III in September 2020, adding bass clarinet, soprano saxophone and electric bass to his own recorded palette and opening the record with "Fantastic Planet," a tribute in sound to René Laloux's 1973 animated film scored with vintage synthesizers.

Guerin became a frequent presence on other musicians' records through the early 2020s: tenor saxophone on bassist Or Bareket's Sahar (Enja Records, 2022), where he also played organ and EWI across the album and mixed the session himself, alongside fellow band members Jeremy Corren on piano and Savannah Harris on drums, with Joel Ross guesting on percussion for the opening track; woodwinds on drummer Harish Raghavan's In Tense (Whirlwind Recordings, 2022); guest tenor saxophone on bassist Ben Tiberio's Rare Peace (Outside In Music, 2021); and repeat studio work with rapper and drummer Kassa Overall, appearing on I Think I'm Good (Brownswood Recordings, 2020) and Animals (Warp Records, 2023). He also guested on pianist Julius Rodriguez's Let Sound Tell All (Verve Records, 2022) and added electronic wind instrument to Marcus Gilmore's live album Journey to the New: Live at the Village Vanguard (Drummerslams, 2025). His father's 2019 album Grass Roots (Louisiana Red Hot Records) carries a credit of its own: Morgan Guerin on keyboards and photography on one track.

His fourth album as a leader, Tales of the Facade (Candid, 2024), was described by NPR as the work of "a jazz artist to watch" and by JazzTimes as coming from "a virtuoso in the truest sense of the word." Recorded almost entirely by Guerin himself in his Brooklyn apartment over the course of a year, it layers self-played bass, saxophones, keyboards, EWI and drums with guest features from Georgia Anne Muldrow, Melanie Charles, Cisco Swank, Zacchae'us Paul, J. Hoard, Kokayi and his brother, vocalist Chase Guerin. He has said the album is built around the idea of community, and its songs move between jazz-rooted instrumental writing, hip-hop verses and R&B melody rather than settling into any one of them.

Guerin's defining trait is instrumental range rather than a single voice: across his own four albums he has played tenor and alto saxophone, soprano saxophone, EWI, bass clarinet, organ, piano, electric bass, drums and percussion, largely layering the parts himself rather than assembling a fixed band. He cites Wayne Shorter as his central influence, drawn as much to Shorter's synthesizer-driven Weather Report period as to his acoustic writing, and to the way Shorter's music borrowed from science fiction and classical form as freely as from the jazz tradition. That interest in science-fiction imagery, and in the analog synthesizers Herbie Hancock and Stevie Wonder used in the 1970s, runs through his own records, which favor slowly unfolding themes and ensemble interplay over solo statements; Guerin has said he is not especially interested in soloing on his own compositions, preferring to let the writing carry the record. On the EWI specifically, his reference point is Michael Brecker, whose synthesizer-horn recordings first drew Guerin to the instrument in his early teens. As a sideman his profile is different: a reliable multi-instrumental utility player, equally credible on saxophone, bass or keys, which is what has made him a recurring presence in Terri Lyne Carrington's Social Science and on records by Esperanza Spalding, Kassa Overall and Julius Rodriguez.