In response to this, the school moved sites to what is now the La Valla Campus (Carlow Street) but had previously been a local business, Mark Foy's Furniture Repository before 1916.

[9] In 1980, however, there was an increased demand for primary education which saw the school extend to teach Kindergarten to Year 6 with enrolment back up to 186 by 1989.

[9] Beginning on 12 October 1992, a construction project which had been approved by St Mary's Parish Priest Fr Joseph Sobb, began.

Being entirely funded by the parents and parishioners of St. Mary's School and Parish, the project included the upgrading and refurbishment of the existing building and outside areas.

[12] In 2012, the North Sydney Parish and St Mary's Catholic Primary School Hall was completed for gathering, recreational and performance purposes.

[9] The most recent phase of construction on the St Mary's campus began in 2017 with the purchase of the property on the West hand side of the school.

After the completion of the construction in February 2018, the demountable classrooms remained to accommodate the students of Marist Catholic College North Shore whilst their campus was renovated in 2020.

The college adopted the colours blue, black and gold and the former Marist Brothers Mosman school motto, "Virtus Ubique Vincit" (Latin) meaning "Courage Conquers All".

[15] This new precinct named Marist Catholic College North Shore consists of two campuses which offer students stage-specific contemporary learning spaces and provide a seamless curriculum pathway from Kindergarten to Year 12.

[18][19] From 3 September 2018; Marist Catholic College North Shore opened its first wave of applications for both boys and girls for Year 7 2021.

[15] Marist Catholic College North Shore runs a selective stream from Years 7 to 9 following the Newman Gifted Education Program.

[25] Colour: Red[26] Named in honour of Barangaroo; a Cammeraygal leader of the Eora Nation at the time of European colonisation.

[25] Colour: Orange[26] Named in honour of Caroline Chisholm; a Catholic philanthropist who provided outreach to vulnerable immigrants to the early European Colony in Australia, particularly women and children.

[25] Colour: Blue[26] Named in honour of the French district of Fourvière where St Marcellin Champagnat and his followers made their pledge promising to devote themselves to the foundation of the Society of Mary, effectively beginning Marist education.

[25] Colour: Purple[26] Named in honour of Mother Eileen O'Connor, Founder of Our Lady's Nurse of the Poor and most likely candidate to be Australia's next saint.

[25] Colour: Green[26] Named in honour of St Francis Xavier; is credited for his idea that the missionary must adapt to the customs and language of the people he evangelises, and for his advocacy of an educated native clergy.

Every second Wednesday following the first four periods, students are sent home allowing staff to work on professional learning programs.

Other sports available throughout the year within the MCC include athletics, cross country running, golf, squash, swimming, and volleyball.t[28]