St Mary's Cathedral College (SMCC) is a systemic coeducational Catholic day school for students, located in the central business district of Sydney, New South Wales, Australia.

From 1910 until 2016 the college was the responsibility of the Congregation of Christian Brothers and was latterly administered via Edmund Rice Education Australia.

Catholic education on the same site as St Mary's Cathedral has been continuous since 1824, except during the construction of the existing college buildings and the associated bishop's quarters (1987–1991).

The Marist Brothers had complained to the Archbishop of Sydney, Cardinal Patrick Francis Moran, about their working and living conditions.

Students at the college have the option to participate in debating, public speaking, mock trial, Duke of Edinburgh Award, and assisting at the Matthew Talbot Hostel in Woolloomooloo.