St. Michael's Choir School is a semi-private Catholic choir school for boys from grades 3-12 in Toronto, Ontario, Canada. It is jointly operated by the Roman Catholic Archdiocese of Toronto and Pontifical Institute of Sacred Music, which manage the school's music curriculum, and the Toronto Catholic District School Board, which administers all other academic subjects, athletics programs, and extracurricular activities. The school is a member of the International Boys' Schools Coalition.

Cathedral schools began in the Early Middle Ages as centers of advanced education, some of them ultimately evolving into medieval universities. Throughout the Middle Ages and beyond, they were complemented by the monastic schools. Some of these early cathedral schools, and more recent foundations, continued into modern times.