The Diocese of Broken Bay is a Latin Church ecclesiastical jurisdiction or diocese the Catholic Church in Australia. It is a suffragan in the ecclesiastical province of the metropolitan Archdiocese of Sydney.

St Leo's Catholic College is a Catholic systemic secondary day school for boys and girls, located in the Upper North Shore suburb of Wahroonga in Sydney, New South Wales, Australia. Situated in the Diocese of Broken Bay, the high school currently has approximately 800 students from Year 7 to Year 12.