| Fat River | |
| Pushpin Map: | Canada Ontario |
| Pushpin Map Caption: | Location of the river mouth in Ontario |
| Subdivision Type1: | Country |
| Subdivision Name1: | Canada |
| Subdivision Type2: | Province |
| Subdivision Name2: | Ontario |
| Subdivision Type3: | Region |
| Subdivision Name3: | Northwestern Ontario |
| Subdivision Type4: | District |
| Subdivision Name4: | Kenora |
| Source1: | Unnamed lake |
| Source1 Coordinates: | 54.3958°N -88.0314°W |
| Source1 Elevation: | 156m (512feet) |
| Mouth: | Fawn River |
| Mouth Coordinates: | 54.6022°N -88.065°W |
| Mouth Elevation: | 112m (367feet) |
| River System: | Hudson Bay drainage basin |
The Fat River is a river in northwestern Kenora District in northwestern Ontario, Canada.[1] It is in the Hudson Bay drainage basin and is a right tributary of the Fawn River.
The Fat River begins at an unnamed lake and flows north to its mouth at the Fawn River. The Fawn River flows via the Severn River to Hudson Bay.