The church, on a hill between St Patrick's Avenue and Stream Street, replaced a Mass-house built on the same site in 1787. John O'Neill, a Belfast architect, designed the church in the Gothic style with a slender tapering spire. It was dedicated by Bishop Dorrian, a native of Downpatrick, on 30 June 1872.
It is an impressive building, with a large rose window in the gable over the entrance door. The altar is of carved stone, the chancel walls are covered in rich mosaic and the high eastern windows are by Meyer of Munich. A major extension, commissioned by the then Canon Maguire, PP and designed by McLean and Forte, Belfast, almost doubles the seating capacity. The extension, which includes a shrine to St Patrick, was dedicated on 23 May 1993 by Patrick Walsh, Bishop of Down and Connor.