This is the largest Catholic church organ in Dublin and has been described as one of the finest in the country. Magahy's 1936 instrument incorporated pipes from an earlier instrument rebuilt by Telford and Telford in 1916, which included parts of a Bevington organ (constructed when the church consisted only of the present transept).

The organ has been rebuilt and restored by Trevor Crowe of Dublin over a two and a half year period. The ethos of this project has been one which allows all pipes to speak musically in a solo capacity as well as having the ability to blend with each other. All seventy of the front pipes, now gilded, speak. They range in size from four feet in height to eighteen feet. There are approximately three thousand pipes behind the casework. New and secondhand (some historic) pipework has been incorporated with suitable original Magahy pipework. The Vox Humana, under expression, is unique in Dublin city.