| Jurisdiction: | Diocese |
| Saint-Denis in France | |
| Latin: | Dioecesis Sancti Dionysii in Francia |
| Local: | Diocèse de Saint-Denis en France |
| Country: | France |
| Province: | Paris |
| Metropolitan: | Archdiocese of Paris |
| Area Km2: | 236 |
| Population: | 1,513,000 |
| Population As Of: | 2010 |
| Catholics: | 660,000 |
| Catholics Percent: | 43.6 |
| Denomination: | Roman Catholic |
| Established: | 9 October 1966 |
| Cathedral: | Cathedral Basilica of St. Denis in Saint-Denis |
| Patron: | Saint Denis of Paris |
| Bishop: | vacant |
| Metro Archbishop: | Laurent Ulrich |
| Archdeacon: | for one--> |
The Diocese of Saint-Denis in Île-de-France (Latin: Dioecesis Sancti Dionysii in Francia; French: Diocèse de Saint-Denis-en-France) is a Latin diocese of the Catholic Church in France.
Erected in 1966 by Pope Paul VI, the diocese was split off from the Archdiocese of Paris and the Diocese of Versailles. Its territory comprises the department of Seine-Saint-Denis.
As of 2011, the diocese remains a suffragan of the Archdiocese of Paris.
As of 2020, the Archdiocese was preparing to twin with the Archdiocese of Owando in the Republic of Congo. This came after a visit from Mgr Pascal Delannoy to the Archdiocese of Owando in July 2020.