Cruciform, the cathedral was built in the Early English, or English Gothic, style of architecture, of limestone, with a low central tower supported on black marble columns.
The exterior walls, apart from the gables, are embattled, and there are two small spires at the west end.
The cathedral is seventy-five yards long, and its width along the transepts is forty-one yards.

Inside, high pointed arches form entrances from the nave into the choir and the two transepts.
 Between the nave and each aisle is a row of five black marble clustered columns, with high moulded arches.
The nave is lighted by a large west window and five clerestory windows, while the aisles each have four windows.
The choir has a groined ceiling with fine tracery and a central group of cherubs.

The baptismal font is medieval and the ancient stone of enthronement for bishops still exists under the seat of the medieval throne in the North Transept, where to this day the bishops of Ossory are enthroned.

The cathedral contains some of the finest ancient monuments in Ireland, including one to Bishop David, and the tombs of many bishops of Ossory and several owners of Kilkenny Castle.
The subjects of the memorials stretch widely across the social spectrum, from the great figures of the House of Ormonde to the humble shoemaker and carpenter.
In the north transept is the ancient Chair of St Kieran, made of carved stone, still used as the chair of enthronement for the Church of Ireland Bishops of Cashel and Ossory.

There are continental carvings on the choir stalls and the hammerbeam roof.
The cathedral has many stained glass windows, including the fine East window, which is a replica of the 13th-century original.

On the eastern side of the south transept is the consistory court, built by Bishop Pococke, with the chapter house to the north of it.
From the north transept a dark passage leads into St Mary's chapel, where the services of St Canice's parish once took place, and a later parish church next to it holds the tomb of Bishop Gafney (died 1576).

Despite some 19th-century restoration, the cathedral has been carefully preserved in its original style and form.
Near the cathedral's east end is Bishop's Palace.
Cruciform, the cathedral was built in the Early English, or English Gothic, style of architecture, of limestone, with a low central tower supported on black marble columns. The exterior walls, apart from the gables, are embattled, and there are two small spires at the west end. The cathedral is seventy-five yards long, and its width along the transepts is forty-one yards.
Inside, high pointed arches form entrances from the nave into the choir and the two transepts.  Between the nave and each aisle is a row of five black marble clustered columns, with high moulded arches. The nave is lighted by a large west window and five clerestory windows, while the aisles each have four windows. The choir has a groined ceiling with fine tracery and a central group of cherubs. 
The baptismal font is medieval and the ancient stone of enthronement for bishops still exists under the seat of the medieval throne in the North Transept, where to this day the bishops of Ossory are enthroned.
The cathedral contains some of the finest ancient monuments in Ireland, including one to Bishop David, and the tombs of many bishops of Ossory and several owners of Kilkenny Castle. The subjects of the memorials stretch widely across the social spectrum, from the great figures of the House of Ormonde to the humble shoemaker and carpenter. In the north transept is the ancient Chair of St Kieran, made of carved stone, still used as the chair of enthronement for the Church of Ireland Bishops of Cashel and Ossory.
There are continental carvings on the choir stalls and the hammerbeam roof. The cathedral has many stained glass windows, including the fine East window, which is a replica of the 13th-century original.
On the eastern side of the south transept is the consistory court, built by Bishop Pococke, with the chapter house to the north of it. From the north transept a dark passage leads into St Mary's chapel, where the services of St Canice's parish once took place, and a later parish church next to it holds the tomb of Bishop Gafney (died 1576).
Despite some 19th-century restoration, the cathedral has been carefully preserved in its original style and form. Near the cathedral's east end is Bishop's Palace.
St Canice's Cathedral