| Jurisdiction: | Diocese |
| São Mateus | |
| Latin: | Dioecesis Sancti Matthaei |
| Rite: | Latin Rite |
| Established: | 16 February 1958 (years ago) |
| Cathedral: | Catedral de São Mateus |
| Area Km2: | 15,104 |
| Population: | 428,339 |
| Population As Of: | 2004 |
| Catholics: | 304,426 |
| Catholics Percent: | 71.1 |
| Metro Archbishop: | Dario Campos, O.F.M. |
| Bishop: | Paulo Bosi Dal'Bó |
| Emeritus Bishops: | Aldo Gerna, M.C.C.I. |
| Website: | www.diocesedesaomateus.org.br |
The Roman Catholic Diocese of São Mateus (Latin: Dioecesis Sancti Matthaei) is a diocese located in the city of São Mateus in the ecclesiastical province of Vitória in Brazil.