The Diocese of Arras (–Boulogne–Saint-Omer) (Latin: Dioecesis Atrebatensis (–Bononiena–Audomarensis); French: Diocèse d'Arras (–Boulogne–Saint-Omer)) is a Latin Church diocese of the Catholic Church in France. The episcopal see is the Arras Cathedral, in the city of Arras. The diocese encompasses all of the Department of Pas-de-Calais, in the Region of Hauts-de-France.
The most significant jurisdictional changes all occurred during the Napoleonic wars. From 1802 to 1841, the diocese was suffragan of the Archdiocese of Paris, shifting away from the Archdiocese of Cambrai, after Napoleon dissolved the massive Archdiocese. After the defeat of Napoleon, the Napoleonic Concordat united the diocese of Arras, diocese of Saint-Omer and diocese of Boulogne together in one much larger diocese. Unlike most of the other dioceses immediately restored, it was not until 1841 that the diocese returned as a suffragan to the Archdiocese of Cambrai.