In 1960, Bishop Charles F. Buddy founded the first co-educational Catholic high school in the Diocese of San Diego.

These boys and girls carried the hopes and best wishes of many people as they attended classes in a three room division of St. Charles School across the street from what would be the future campus.

The original campus was located in South San Diego, near the intersection of Coronado Avenue and Thermal Street.

Its facilities include the Marian chapel, a track and football stadium, baseball and softball diamonds, tennis courts, a full-service 800-seat theater, a competition swimming pool, a basketball/volleyball gym, and an environmentally friendly "earth bench".

Most recently, the Mater Dei football team won the CIF Division 5AA State Championship in December 2015 against Immanuel High School of Reedley, CA.