| Root River | |
| Pushpin Map: | Canada Ontario |
| Pushpin Map Caption: | Location of the mouth of the Root River in Ontario |
| Subdivision Type1: | Country |
| Subdivision Name1: | Canada |
| Subdivision Type2: | Province |
| Subdivision Name2: | Ontario |
| Subdivision Type4: | District |
| Subdivision Name4: | Algoma |
| Source1: | Upper Island Lake |
| Source1 Location: | Island Lake |
| Source1 Coordinates: | 46.6694°N -84.2586°W |
| Source1 Elevation: | 335m (1,099feet) |
| Mouth: | St. Marys River |
| Mouth Location: | Sault Ste. Marie |
| Mouth Coordinates: | 46.5422°N -84.2125°W |
| Mouth Elevation: | 181m (594feet) |
| Tributaries Left: | Crystal Creek, Coldwater Creek |
| Tributaries Right: | West Root River |
The Root River is a river in Algoma District in northeastern Ontario, Canada. It flows from Upper Island Lake at the community of Island Lake to its mouth at the St. Marys River.
From Upper Island Lake, the river heads south and parallels Ontario Highway 552 to that highway's beginning at Ontario Highway 17 at the community of Heyden, then Highway 17 to the Odena neighbourhood of Sault Ste. Marie. It then heads east and southeast to reach its mouth at the St. Marys River, which forms a small delta called Bells Point.