The Parramatta Marist High School is an independent Roman Catholic single-sex secondary day school for boys, located in Westmead, a suburb of the western region of Sydney, New South Wales, Australia.

Parramatta Marist began under the direction of George Morley.

The school was transferred to the site of the present St Patrick's Cathedral in 1837.

Secondary classes were moved in that year to Westmead, leaving only primary classes at the Parramatta site.

In 2008, Parramatta Marist High introduced project-based learning into Year 9 which focused on group learning.