In 1894, the Congregation of Christian Brothers, at the invitation of Bishop Matthew Gibney, opened CBC Perth and took over the administration of St Patrick's as well as providing teaching staff.
In 1938, the boarders at CBC Perth and a number of day students transferred to the new Aquinas College campus at Salter Point.
[1] In 1937, the principals of CBC Highgate, CBC Fremantle and St Patrick’s Boys' School founded the Christian Brothers Secondary Schools Sports Association (now called the Associated & Catholic Colleges of Western Australia.)
[2] As the Perth metropolitan area grew, the number of Catholic parish primary schools in the suburbs also increased.
In 1948, at the insistence of Archbishop Prendiville, the Brothers agreed to make St Patrick's a secondary technical school.