The Strathfield Campus (Mount Saint Mary) site was formerly part of land belonging to the St James Church of England in 1823. In 1886, three joint tenants of the land built a large country mansion called Mount Royal.
After the last of the three men passed away, Mount Royal had various occupants, including the Rt Hon Sir George Houston Reid (Premier of New South Wales from 1894 to 1899 and Prime Minister of Australia from August 1904 until July 1905), who was resident during 1903 and part of 1904.
The property was acquired by the Christian Brothers on 20 December 1907 and became the centre of the Christian Brothers Congregation for Australia and New Zealand. The Brothers also acquired two adjoining properties.
In 1908, the Mount Saint Mary College was inaugurated for the training of teaching monks. In 1974, the first male lay students were enrolled in the College and in 1975, the Diploma in Primary/Junior Secondary Teaching was approved as a course in Advanced Education. A Postgraduate Diploma in Educational Studies, Pastoral Guidance was introduced in 1980. In the same year, approval was obtained for a joint Bachelor of Education with Polding College to teach a Years 5-8 program which commenced in 1982.
In 1981, the Federal Government required specified Colleges in each State to amalgamate. Catholic Teachers' College and Polding College were among the institutions nominated for amalgamation. Mount Saint Mary College joined in the amalgamation, which was effected in January 1982 as Catholic College of Education Sydney.
At the end of 1990, the Catholic College of Education Sydney formally handed responsibility for the College and its operations to Australian Catholic University (ACU).
On 7 January 1993, the Christian Brothers sold 5-8 hectares of the property to the Diocese of Sydney, who hold the property in trust on behalf of ACU.
In 2002, ACU purchased the Our Lady of Loreto Nursing Home from the St Vincent de Paul Society. The building was extensively developed and re-named after ACU’s Foundation Chancellor, His Eminence Cardinal Edward Clancy AC.