Mason Jeffery-Off is a Canadian double bassist, electric bassist, composer and bandleader based in Montréal. Originally from Ottawa, Ontario, Jeffery-Off graduated with a Bachelor’s Degree in Jazz Performance at McGill University in 2026. There, he studied with Ira Coleman, Rémi-Jean LeBlanc for bass and John Hollenbeck for composition. An on-call bassist, he has performed with the likes of Jean-Michel Pilc, Darrell Green, Kevin Dean and the National Arts Centre Orchestra.

At 18, Jeffery-Off was one of 16 international jazz musicians under the age of 25 to be selected for Betty Carter’s Jazz Ahead, a performer-composer residency located at the John F. Kennedy Center for the Arts in Washington DC. In 2024, he received the Hnatyshyn Developing Artist Grant (Oscar Peterson Grant for Jazz Performance).

Jeffery-Off currently leads Marvelous Creatures, a seven-piece ensemble featuring his own compositions derived from written and spoken language. He also co-leads VOOMM, an experimental dance band.

To Jeffery-Off, “Musicians share a special bond and to nurture it we must be open to each other's ideas, making them work in tandem. My goal is to abandon my preconceptions and serve the spirit of the moment. It is this humanity and spontaneity that bridge the gap between music and listener and, in turn, connects us all.”