Aloysius Ambrozic was born in Dobrova, Slovenia, the second of the seven children of Aloysius Ambrozic and his wife, Helena Pecar. He attended elementary school in Dobrova and high school in Ljubljana. In May, 1945, the entire family fled to Austria, where they lived in refugee camps at Vetrinj, Peggez and Spittal an der Drau. While in these camps, Aloysius completed his high school education.
In September of 1948 the family immigrated to Canada and settled near Toronto. Shortly afterwards, Aloysius entered St. Augustine's Seminary to study philosophy and theology. On June 4, 1955, he was ordained a priest of the Archdiocese of Toronto by His Eminence, James C. Cardinal McGuigan.
The first year of his priesthood he served as Curate at St. Teresa's Parish in Port Colborne, Ontario. He then taught Latin for a year at St. Augustine's Seminary, Toronto. The years 1957-1960 were devoted to postgraduate studies in Rome, where he received a Licentiate in Theology at the Angelicum and a Licentiate in Sacred Scripture at the Pontifical Biblical Institute.
Returning to Toronto, Fr. Ambrozic taught scripture at St. Augustine's Seminary from 1960-67. In 1967 he began further studies in Germany, obtaining a Doctorate in Theology from the University of Würzburg in 1970.