Larnell Lewis was born in Toronto on March 22, 1984, the oldest of three children. His parents, Oral and Maureen Lewis, came to Canada from St. Kitts in 1983; his father plays several instruments and his mother sings. His sister Cathy sings and plays drums, and his younger brother Ricky became the touring drummer for The Weeknd. Larnell started on the drums in church as a small child, and the church repertoire was his first curriculum: gospel, along with soca, calypso, reggae, zouk and funk. He also studied electric bass and piano, which later let him add keyboards and synthesizer parts to his own records.

At Mayfield Secondary School he was valedictorian of his music class, and in 2003 he won the Yamaha Kando Award at MusicFest Canada. At about 17 he was hired on bass by the Toronto singer Salome Bey and her group the Relatives, and the drummer Archie Alleyne became a mentor who brought him into projects such as the Evolution of Jazz. At Humber College he received the Oscar Peterson Award for Outstanding Achievement in Music in 2004, the highest award the school gives, with a $5,000 scholarship attached. On August 14, 2003, the night of the Northeastern blackout, he was playing for the gospel singer Amoy Levy at the Honey Jam showcase at the Phoenix in Toronto and met the steelpan player Joy Lapps, who later became his wife and a frequent collaborator.

Through the 2000s he worked as a Toronto sideman across gospel, jazz and pop. He is credited on Rhema Worship & Praise's The Experience (2006) and the Toronto Mass Choir's Going Home (2007), both gospel releases, and on the pianist and singer Laila Biali's From Sea to Sky (2007) and Tracing Light (2010), the Mike Janzen Trio's Mombácho (2008) and a long run of Toronto jazz and soul records after that. He plays on Emilie-Claire Barlow's Clear Day (2015, with the Metropole Orkest), which won a JUNO Award, and on bassist Mike Downes's JUNO-winning Root Structure. His own biography also lists the gospel singer Fred Hammond among the artists he has played with. By February 2021 he had been a music professor at Humber for eleven years, and his official biography still lists him as a Professor of Music.

His breakthrough on the international stage came with Snarky Puppy. His own biography dates his membership from 2012. On We Like It Here, recorded live over four nights in October 2013 at Kytopia in Utrecht and released on February 25, 2014, he learned most of the music on the flight to the Netherlands, having played only two of the pieces before the session. He is also on Family Dinner, Volume Two (released February 12, 2016) and on Culcha Vulcha (April 29, 2016), which won the Grammy for Best Contemporary Instrumental Album at the 59th Grammy Awards in February 2017. He shared the September 2016 cover of Modern Drummer with the band's other drummers, Robert "Sput" Searight and Jason "JT" Thomas. He appears on Immigrance (2019), on Empire Central (September 30, 2022), recorded live in front of an audience over eight days at Deep Ellum Art Company in Dallas, which won the same Grammy category at the 65th Grammy Awards in February 2023, and on Somni, the band's live collaboration with the Metropole Orkest recorded in Utrecht in January 2025 and released in November 2025, where he is one of four drummers. The orchestra partnership began earlier: in 2018 he played the North Sea Jazz Festival with Snarky Puppy and the Metropole Orkest and made his Carnegie Hall debut with them.

Outside the band he has worked widely with visiting and international artists. His official biography lists tours or engagements with Quincy Jones, Gregory Porter, Benny Golson, Lalah Hathaway, Jacob Collier, John Scofield, Pat Metheny, Lisa Fischer, Kurt Elling, Gary Burton, Etienne Charles and Laila Biali. He was musical director for a performance at the Toronto International Film Festival premiere of Quincy, the documentary about Jones, leading singers including Yebba, Mark Ronson and Chaka Khan, and in 2018 and 2019 he accompanied Jones in concerts in London, Paris and Montreal. In February 2021 a video for the Drumeo channel, in which he heard Metallica's "Enter Sandman" once and then played the whole drum part, went viral, passing 19 million views by February 2025.

His own records came late and carry his full range. In the Moment (Larnell Lewis Music, June 15, 2018) is a studio album on which he wrote all the music and co-produced it with Eddie Bullen. He plays drums throughout, adds keyboards, synthesizer, percussion and vocals on selected tracks, and leads a band that includes Mike Downes, Robi Botos, Michael Shand, Rob Christian and William Sperandei, with Shaun Martin and Mark Lettieri guesting on the closing track. It earned a 2019 JUNO nomination for Jazz Album of the Year: Solo, in a category won by Botos's Old Soul, a record on which Lewis plays drums. Relive the Moment (November 20, 2020) re-recorded drum parts for six of the In the Moment pieces and added one new piece, "The Forgotten Ones," a long drum solo over an Afro-Caribbean groove. Slice of Life (March 22, 2024) is a set of pieces about being a husband and father, with Joy Lapps on steelpan, and brought a second JUNO nomination in the same category in 2025, won that year by André Leroux. The Caribbean Christmas Mixtape, Vol. 1 (November 15, 2024), made with Lapps, puts classic Christmas songs through soca, zouk, reggae and ska. Alongside the Grammys, he received the Toronto Arts Foundation's Emerging Jazz Award in 2017 and the Toronto Musicians' Association's Musician of the Year award in 2018. He is based in Toronto, and in June 2026 he played the Ottawa Jazz Festival with his own band featuring Joy Lapps.

Lewis is a groove drummer first, and his reference points are the ones he grew up with: the gospel, soca, calypso, reggae, zouk and funk he learned in church. Reviewers describe his playing as combining the technical intricacy of jazz fusion, the groove of funk and the improvising instincts of bebop drummers, and one reviewer called Relive the Moment a collection of funk and neo-soul. His 2024 album mixes jazz fusion with Afro-Caribbean and Brazilian rhythms and R&B, and the Caribbean Christmas record draws on soca, zouk, reggae and ska.

The jazz side is real and documented, though it is a side. He is a Humber College professor, his albums are nominated in JUNO jazz categories, he has worked with Gary Burton, Benny Golson, Kurt Elling and Pat Metheny, and the Toronto Arts Foundation honoured him with its Emerging Jazz Award. Snarky Puppy itself plays instrumental music that blends jazz, funk, rock and world music, and Empire Central was conceived as an homage to Dallas's black music, with gospel and R&B among its stated influences. AllMusic files Lewis's own catalog under gospel rather than jazz. His church and Caribbean heritage are the starting point of his story rather than a footnote, and a fair description is a gospel- and funk-rooted drummer who works mostly in the jazz world, with records that sit between the two.