| Jurisdiction: | Diocese |
| Nnewi | |
| Latin: | Dioecesis Nneviensis |
| Country: |  Nigeria |
| Territory: | northern portion of Anambra State including these local government areas: Nnewi North and Nnewi South, Ekwusigo and Ihiala (minus Uli and Amorka) |
| Province: | Onitsha |
| Metropolitan: | Archbishop of Onitsha |
| Coordinates: | 6.0197°N 6.9147°W |
| Area Km2: | 662 |
| Area Sqmi: | 225 |
| Population: | 687,453 |
| Population As Of: | 2004 |
| Catholics: | 458,302 |
| Catholics Percent: | 66.7 |
| Parishes: | 100 |
| Denomination: | Roman Catholic |
| Established: | 28 November 2001 |
| Priests: | 205 |
| Bishop: | Most Rev. Jonas Benson Okoye |
| Suffragan: | for one --> |
| Archdeacon: | for one--> |
| Map: | Nigeria Anambra State map.png |
| Website: | www.nnewicathdiocese.org |
| Footnotes: | [1] |
The Roman Catholic Diocese of Nnewi (Latin: Nnevien(sis)) is a diocese located in the city of Nnewi in the ecclesiastical province of Onitsha in Nigeria.
The Cathedral is Cathedral of Our Lady of Assumption in Nnewi.