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.

Diocese of Saint-Denis in France Dioecesis Sancti Dionysii in Francia Diocèse de Saint-Denis en France
Cathedral Basilica of St. Denis
Location
Country	France
Ecclesiastical province	Paris
Metropolitan	Archdiocese of Paris
Statistics
Area	236 km2 (91 sq mi)
Population - Total - Catholics	(as of 2010) 1,513,000 660,000 (43.6%)
Information
Denomination	Roman Catholic
Sui iuris church	Latin Church
Rite	Roman Rite
Established	9 October 1966
Cathedral	Cathedral Basilica of St. Denis in Saint-Denis
Patron saint	Saint Denis of Paris
Current leadership
Pope	Francis
Bishop	Pascal Delannoy
Metropolitan Archbishop	Laurent Ulrich
Website
saint-denis.catholique.fr

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.