Mason Jeffery-Off is a Canadian double bassist, electric bassist, composer and bandleader based in Montréal, Canada. Originally from Ottawa, Ontario, Jeffery-Off is in the fourth year of his Bachelor’s Degree in Jazz Performance at McGill University. There, he has studied with Ira Coleman and Rémi-Jean LeBlanc. An on-call Montréal bassist, he has performed with the likes of Jean-Michel Pilc, Darrell Green, Caity Gyorgy and Kevin Dean.

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). Mason is also the winner of two Downbeat Student Music Awards in 2025; one for Undergraduate Small Jazz Combo with Leo Codiga & The Southwest Corridor, and one for Undergraduate Outstanding Performance with the McGill Jazz Vocal Conglomerate.

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.”