| Jurisdiction: | Diocese |
| Hearst–Moosonee | |
| Latin: | Dioecesis Hearstensis et Musonitana |
| Coat: | File:Diocese_of_Hearst–Moosonee.jpg |
| Coat Size: | 200px |
| Coat Caption: | Coat of Arms |
| Country: |  Canada |
| Province: | Ontario |
| Area Km2: | 1,108,830 |
| Population: | 66,820 |
| Population As Of: | 2021 |
| Catholics: | 26,520 |
| Catholics Percent: | 39.7 |
| Parishes: | 25 |
| Denomination: | Catholic Church |
| Sui Iuris Church: | Latin Church |
| Rite: | Roman Rite |
| Established: | 3 December 1938 |
| Cathedral: | Notre-Dame-de-l'Assomption Cathedral |
| Priests: | 20 |
| Bishop: | Pierre Olivier Tremblay, O.M.I. |
| Emeritus Bishops: | Vincent Cadieux, OMI Robert Bourgon |
The Diocese of Hearst–Moosonee (Latin: Dioecesis Hearstensis) is a Latin Church ecclesiastical territory or diocese of the Catholic Church in Ontario. The diocese was erected on 3 December 2018 through the unification of the Diocese of Hearst and the Diocese of Moosonee.[1] The Diocese of Hearst evolved from the Prefecture Apostolic of Northern Ontario erected on 18 April 1919. The Diocese of Hearst–Moonosee is a suffragan diocese in the ecclesiastical province of the metropolitan Archdiocese of Ottawa-Cornwall.
The territory that would form the diocese was elevated to an apostolic vicariate on 17 November 1920.
| Year | Along with | To form | |
|---|---|---|---|
| 1938 | Diocese of Haileybury | Vicariate Apostolic of Baie de James |