Most of the land on which our Parish church and school stands was previously owned by Mrs Edith Santon who sold it to the Parish as she did not want it subdivided. While still part of Sacred Heart Parish Diamond Creek, the first Masses were celebrated in the original Santon homestead in 1952. The house was later to be used as the Presbytery until about 1970 when it was demolished to clear the site for the building of our church.
In 1954 in preparation for the creation of the new Immaculate Conception Parish, but always commonly referred to as St Mary’s, work commenced on the five original school classrooms under builder W.D. Henderson, and officially opened in 1955 by Archbishop Daniel Mannix. Mass was celebrated on weekends in two of these classrooms and from 1959 in the school wooden hall. Construction of our church commenced in 1971 from a design by Architect Max Chester. The Builder was H.F. Yunken of Richmond. Our church was officially opened and blessed on 27th October 1971 by the Most Reverend James Robert Knox. The new extension to the front, including the Gathering Space, of the church was completed in 2011.
The first Parish Priest of St. Mary’s was Fr. Thomas Ashe, formally Parish Priest of Sacred Heart Diamond Creek, and he remained with our community until his death in 1971. He was followed by Fr. James (Jim) Kierce who faithfully served the community of St. Mary’s until his retirement in 2003. He later passed away in 2017 with his funeral service being celebrated at St. Mary’s. In 2003 Fr. Steven Rigo was appointed as Parish Priest where he has remained up until the present day continuing to build on the foundations laid by Fr’s. Ashe and Kierce. Many Assistant Priests, Pastoral Associates, School Principals and teachers as have many parishioners have served the Parish over the years.
As the population of the area increased, separate parishes were created from areas of the original St Mary’s Parish - St Francis Xavier Parish Montmorency in 1961 and St Thomas the Apostle Greensborough North in 1986.
In 1999 a Parish Review developed a Parish Pastoral Plan including the Parish Vision “To be a vibrant Christian community engaging with the world.”
In January 2017, on the request of Archbishop Hart, the parishes of Diamond Creek and Greensborough North were partnered with the Parish of St. Mary's Greensborough with Fr. Steven appointed as Parish Priest of all three parishes.