Cathedral High School was founded by Archbishop John J. Cantwell as the first Los Angeles Archdiocesan high school for boys in the fall of 1925. The Christian Brothers have operated Cathedral High School since its opening. Cathedral is located on the site of Old Calvary Cemetery just northeast of the Civic Center and in view of Our Lady of the Angels Cathedral.
In 1923 the Christian Brothers arrived in Los Angeles and taught 7th and 8th grade boys at Sacred Heart Parish, Lincoln Heights. In 1924 a 9th grade was added. The Brothers and 9th and 10th grade students moved to the new high school on Bishops Road at the beginning of the 1925-1926 school year. Cathedral High School officially opened on September 1, 1925.