In 1980, 10.1079 hectares of land, originally vested in the St Brigid's Convent of Mercy Perth Inc, was held in trust for purpose of "School and Convent". A decade later an Interim Board was formed comprising Representatives from the Local Community, the Archbishop, Principals and the Catholic Education Office. 

In March 1991, the Catholic Education Commission formally approved the proposal to establish Mater Dei College and an architect was appointed. The following year, the land was revested on 20th March under the Roman Catholic Archbishop of Perth for the purpose of "School" consisting of 8.1078 hectares. Two buildings were erected and eight staff members were appointed.

Archbishop Barry Hickey and Director of Catholic Education Therese Temby Officially Blessed and Opened the College respectively in 1993, and 108 students commenced on the 4th February. The Curriculum consisted of Religious Education, English, Japanese, Mathematics, Social Studies, Science, and Physical and Health Education.

In 1994, the School Board was elected by the Community for the first time and two planning committees of Technology and Curriculum were established. Stage Two of the building program was completed and opened in March the following year by Bishop Robert Healy and Sister Kaye Bolwell of the Sisters of Mercy - whom the Mercy Block is named after in honour of their generosity in donating the land for the College. Stage Three construction of Science Lab additions and a new Administration Block commenced and the Year 11's hosted exchange students from Edogawa Gakuen Toride High School in Japan for the first time.

Mater Dei has always enjoyed excellent growth and by 1997 the enrolment had climbed to 810 students, with 52 teaching staff and 10 support staff. The House System was introduced comprised of a horizontal homeroom structure within four Houses. 

In 1999, the College was a maximum six stream school with an accredited Vocational Education Course and now catered for students with disabilities. Construction commenced on the new hall and gymnasium, which we now know as The Bernie Boss Hall, named after the Inaugural Principal.

In 2003, after the Pastoral Care System had been revised, Vertical Homerooms were introduced into the House System and the Board developed a Capital Development Plan to enhance the learning environment for the students.

By 2007, alterations to the Salvado Block and extensions to Music and Technical Arts rooms were completed, with construction beginning on extensions to the Yellagonga Building which houses Administration and Staff.

In 2009, Mater Dei was recognised as a Centre of Excellence in Languages and a dedicated Languages facility for the study of Indonesian and Japanese was incorporated into the new Year 7 block.

In 2010, Year 7 students became part of the Mater Dei Community for the first time, with two new Houses formed and the total College enrolments reaching 1030. The Benedict Building was completed by Term 2 and MacBook Laptop Computers were introduced for all Year 7 and 8 students.

This year, the College celebrates its 25th anniversary. This will be a momentous year to mark past achievements of the College over its many periods of development and provides an opportunity to look forward with a clear vision for the future.

Mater Dei College continues to develop and grow into a well-respected educational facility and a centre of influence in the local community.