| Manganuiohou River | |
| Pushpin Map: | New Zealand#New Zealand North Island |
| Pushpin Map Size: | 270px |
| Pushpin Map Caption: | Mouth of the Manganuiohou River |
| Source1 Coordinates: | -38.7617°N 177.1773°W |
| Mouth Location: | Waiau River |
| Mouth Coordinates: | -38.9028°N 177.439°W |
| Subdivision Type1: | Country |
| Subdivision Name1: | New Zealand |
| Length: | 190NaN0 |
| Progression: | Manganuiohou River → Waiau River → Wairoa River → Hawke Bay → Pacific Ocean |
| Tributaries Left: | Te Mahanga Stream, Motumota Stream |
| Waterfalls: | Te Rerehautai Falls |
The Manganuiohou River is a river of the northeast of New Zealand's North Island. It flows southwards from its source in Te Urewera National Park immediately to the northwest of Lake Waikaremoana, and joins with the Waiau River at the park's southwestern boundary.