Emmet Harley Cohen was born on May 25, 1990, in Miami, Florida. He started piano at the age of three with the Suzuki method and took keyboard lessons as a boy at the University of Miami's Frost School of Music in Coral Gables before his family moved to New Jersey, when he was ten. He grew up in Montclair, studied classical piano in the pre-college program of the Manhattan School of Music, and went to Montclair High School, where he played in the Gibson/Baldwin Grammy Jazz Ensemble with drummer Bryan Carter, trumpeter Benny Benack III, saxophonist Grace Kelly and saxophonist Chad Lefkowitz-Brown. Outside school he went to jazz clubs on his own and with his father, sat in with the musicians he met there, and learned the Hammond B-3 organ at Cecil's Jazz Club in West Orange, New Jersey, playing sessions led by saxophonist Bruce Williams. He won a National YoungArts Foundation award in jazz in 2009.

Cohen earned a bachelor's degree in jazz piano at the Frost School of Music, graduating in 2012, and was mentored there by the school's dean, the pianist Shelly Berg, whom he had met at the Jazz Band of America festival. He recorded his first album, In the Element, in 2010 as a student, with trumpeter Greg Gisbert, bassist Joe Sanders and drummer Rodney Green. In 2011 he won the Phillips jazz piano competition run by the University of West Florida and placed third in the Thelonious Monk International Piano Competition at the Kennedy Center, behind the winner, pianist Kris Bowers; the finalists were received at the Oval Office by President Barack Obama on September 13, 2011. He returned to New York after graduating and completed a master's degree at the Manhattan School of Music in 2014 on a full scholarship. His next two records came out in those years: Infinity (2013), recorded in Matera, Italy, with bassist Giuseppe Venezia and drummer Elio Coppola,and Questioned Answer (2014, Hollistic MusicWorks), a set of quartet and duo pieces recorded in 2012 with trumpeter Brian Lynch, bassist Boris Kozlov and drummer Billy Hart.

The idea for his Masters Legacy Series came from a long bus ride with saxophonist Jimmy Heath, who spent the trip talking about the context in which the music had been made. The first volume, with drummer Jimmy Cobb, was recorded live on March 16, 2016, at the DiMenna Center in New York and issued by Cellar Live in January 2017. Volume 2 captured bassist Ron Carter live in Vancouver on June 29, 2017 (Cellar Live, 2018); volume 3 paired saxophonist Benny Golson with drummer Albert "Tootie" Heath (2019); volume 4 featured saxophonist George Coleman (recorded March 19, 2018, released 2019); and volume 5, with tenor saxophonist Houston Person, was recorded on May 16, 2023, at Van Gelder Studio in Englewood Cliffs, New Jersey, and released on November 10, 2023. Between the first volumes the Emmet Cohen Trio, with bassist Russell Hall and drummer Kyle Poole, recorded Dirty in Detroit live at the Dirty Dog Jazz Café in Grosse Pointe Farms, Michigan, on September 15, 2017, and released it themselves around the end of 2018. Cohen also played piano for other leaders in these years, among them drummer Herlin Riley (New Direction, 2016, and Perpetual Optimism, 2019, both on Mack Avenue) and singer Veronica Swift. For a period of years he was also the Hammond B-3 organist-in-residence at the Smoke Jazz & Supper Club in New York.

In 2019 Cohen won the American Pianists Awards, which carried the Cole Porter Fellowship in Jazz, a recording contract with Mack Avenue Records and a two-year artist residency at the University of Indianapolis. When the pandemic closed New York's clubs in March 2020, he, Hall and Poole began streaming a weekly concert, Live from Emmet's Place, from his Harlem apartment, modeled on the Harlem rent party. Guests over the next years included Houston Person, Joe Lovano, Brad Mehldau, Christian McBride, Eddie Henderson, Sheila Jordan, Victor Lewis, Nicole Glover and Samara Joy, and by April 2022 the weekly series' videos had been viewed more than eleven million times. In October 2020 he led the trio, with bassist Yasushi Nakamura standing in for Hall, on a dozen-date tour of Italy, Germany, Switzerland and Austria. He started a series of free online master classes, Emmet's Place Education, in December 2021, and the Jazz Journalists Association named him Up and Coming Musician of the Year (2021) and Live-Stream Producer of the Year (2022). The last broadcast from the apartment was on October 6, 2025, and the series moved to the Power Station recording studio, where it opened on December 8, 2025, with Joshua Redman.

His first Mack Avenue album, Future Stride, appeared on January 29, 2021, and was followed by Uptown in Orbit (October 28, 2022) and Vibe Provider (August 23, 2024), a record dedicated to his late friend Funmi Ononaiye. Vibe Provider has Philip Norris on bass and a horn section of tenor saxophonist Tivon Pennicott, trumpeter Bruce Harris and trombonist Frank Lacy. His fourth Mack Avenue album, Universal Truth, was recorded on October 5, 2025, at Sear Sound in New York and released on May 29, 2026, in the centennial year of Miles Davis and John Coltrane; it reunites Ron Carter and George Coleman on "My Funny Valentine" more than sixty years after they played it on the Davis album of that name. In February 2026 the DC Jazz Festival named Cohen and pianist Janelle Gill its Artists-in-Residence for the year, with duties that include workshops, artist talks and guest curation.

Cohen plays mainstream jazz piano with a long historical memory. He has said he wanted to bring stride into current playing because he loves the music of Fats Waller, Willie "The Lion" Smith, Earl Hines, James P. Johnson and Art Tatum, and because stride is one of the hardest and most exciting things a jazz pianist can take on; he adds that Thelonious Monk learned it from Mary Lou Williams, so anyone who loves Monk should study it. That idea gave Future Stride its title, and the trio's records blend styles from the past, mixing originals with vintage tunes, all played with a modern sensibility. He also has extensive classical training, which shows in his technique and in the quotations that turn up in his improvisations. Writers have stressed the same few qualities: a wide knowledge of jazz history, fast and clean technique, and a trio that plays with an almost telepathic feel after years of working and living together. Giovanni Russonello of the New York Times praised his easy command of the keyboard, and Dave Gelly of the Guardian called Future Stride charming. His bandstand approach is as much teaching as performing: he uses the Masters Legacy Series and Live from Emmet's Place to put younger and older players on the same stage, and he has described the aim as passing jazz's unwritten history from one generation to the next. Critics' and readers' polls in DownBeat have placed him among the leading pianists of his generation, including first place among rising-star pianists in the 2022 critics' poll and first place among rising-star groups for his trio in 2024.