| Firesteel River | |
| Pushpin Map: | Canada Ontario |
| Pushpin Map Caption: | Location of the mouth of the Firesteel River in Ontario |
| Subdivision Type1: | Country |
| Subdivision Name1: | Canada |
| Subdivision Type2: | Province |
| Subdivision Name2: | Ontario |
| Subdivision Type4: | District |
| Subdivision Name4: | Thunder Bay |
| Length: | 55km (34miles) |
| Source1: | Trap Lake |
| Source1 Coordinates: | 49.2117°N -90.4494°W |
| Source1 Elevation: | 495m (1,624feet) |
| Mouth: | Seine River |
| Mouth Coordinates: | 49.0297°N -90.9458°W |
| Mouth Elevation: | 437m (1,434feet) |
| River System: | Hudson Bay drainage basin |
| Tributaries Left: | Hay River (Canada), East Firesteel River |
| Tributaries Right: | Trewartha Creek, Beaver River, North Firesteel River |
The Firesteel River is a river in Thunder Bay District, northwestern Ontario, Canada in the Hudson Bay drainage basin. It flows from Trap Lake, 3km (02miles) east of the Canadian National Railway location of George and 19km (12miles) north of the community of Upsala, southwest under the Canadian National Railway, the Canadian Pacific Railway mainline and Ontario Highway 17 to its mouth at the Seine River, 28km (17miles) west of Upsala.