A chapel from the penal period existed between Carlow College and the Dublin Road. In 1787 Dr. Henry Staunton, Parish Priest of Carlow, built a sizeable Church on the later Cathedral site.
The Cathedral was completed in 1833 and the old church was demolished. Part of its transept walls were retained and incorporated into the new structure. It is gothic in design. Thomas Cobden was the main architect. The magnificent tower and lantern, reaching 46 metres, was inspired by the cloth Hall at Burges in Belgium.