| Wainui River | |
| Pushpin Map: | New Zealand Northland |
| Pushpin Map Alt: | Map of Northland |
| Pushpin Map Caption: | Location of the Wainui River in Northland |
| Mouth Coordinates: | -35.0855°N 173.6415°W |
| Subdivision Type1: | Country |
| Length: | 18km (11miles) |
The Wainui River is a river of the Northland Region of New Zealand's North Island. It flows generally northeast from its sources at the eastern end of the Maungataniwha Range to reach the Oruaiti River five kilometres southwest of the Whangaroa Harbour.