| Hewitson River | |
| Pushpin Map: | Canada Ontario |
| Pushpin Map Caption: | Location of the mouth of the Hewitson River in Ontario |
| Subdivision Type1: | Country |
| Subdivision Name1: | Canada |
| Subdivision Type2: | Province |
| Subdivision Name2: | Ontario |
| Subdivision Type4: | District |
| Subdivision Name4: | Thunder Bay |
| Length: | 2.3km (01.4miles) |
| Source1: | Whitesand Lake |
| Source1 Coordinates: | 48.8467°N -87.3983°W |
| Source1 Elevation: | 283m (928feet) |
| Mouth: | Lake Superior |
| Mouth Coordinates: | 48.8353°N -87.4097°W |
| Mouth Elevation: | 180m (590feet) |
| River System: | Lake Superior |
The Hewitson River is a short river in Thunder Bay District, northwestern Ontario, Canada. When the Canadian Pacific Railway was being constructed along the north shore of Lake Superior 1882–1885, the river was known as Maggot River.
The river begins at Whitesand Lake and flows over a series of falls, called the Rainbow Falls, then is crossed by Highway 17, and finally flows into Lake Superior. The mouth is about 8km (05miles) east of the community of Rossport and 10km (10miles) west of the community of Schreiber
Several campgrounds of Rainbow Falls Provincial Park lie astride the river.