The Diocese of Down and Connor, (Latin: Dioecesis Dunensis et Connorensis; Irish: Deoise an Dúin agus Chonaire) is a Latin Church ecclesiastical territory or diocese of the Catholic Church in Northern Ireland.

The territorial remit of the diocese includes much of counties Antrim and Down, including the cities of Belfast, Lisburn and Bangor, and the large towns Antrim, Ballymena, Carrickfergus, Downpatrick, Holywood, Larne and Newtownards.

The population of the diocese is about one million, of which approximately 30% are Roman Catholic with Sunday mass attendance estimated at 20%.

In 1670, as an effect of the Reformation, wars, and penal laws, in the whole of Down and Connor there were only 2,500 Catholic families.

They spoke with the Pope for 20 minutes privately in which they discussed things like education, child sexual abuse, peace and reconciliation in Northern Ireland.