The ceremony was held virtually on Monday due to the COVID-19 pandemic. The event was originally going to take place on March 15 with Cara as host.
Cara won three awards including Album of the Year and Pop Album of the Year for The Pains of Growing and Songwriter of the Year.
Mendes, meanwhile, won Single of the Year for his collaboration with Camila Cabello "Senorita" and Artist of the Year.
Avril Lavigne won the Juno Fan Choice Award, the only category voted on by fans.
Billie Eilish won International Album of the Year for When We All Fall Asleep, Where Do We Go?, Loud Luxury won Group of the Year, Lennon Stella won Breakthrough Artist of the Year, Neon Dreams won Breakthrough Group of the Year, and Tory Lanez won Rap Recording of the Year for "Freaky."
A full list of winners can be found on the official website of the Juno Awards.