| Manganui River | |
| Mouth Location: | Wairoa River |
| Subdivision Type1: | Country |
| Subdivision Name1: | New Zealand |
| Length: | 53km (33miles) |
New Zealand's largest Manganui River is a river of the Northland Region of New Zealand's North Island. It follows a generally westward course from its sources west of Ruakaka before its outflow into the Wairoa River 5km (03miles) east of Dargaville. The river's lower course is noted for its convoluted, winding path through low-lying swampy terrain, and several oxbow lakes are associated with this stretch of the river.