| Seine River 23B | |
| Official Name: | Seine River Indian Reserve No. 23B |
| Settlement Type: | Indian reserve |
| Pushpin Map: | Canada Ontario |
| Pushpin Mapsize: | 200 |
| Coordinates: | 48.6667°N -138°W |
| Subdivision Type: | Country |
| Subdivision Type1: | Province |
| Subdivision Type2: | District |
| Subdivision Name2: | Rainy River |
| Subdivision Type3: | First Nation |
| Subdivision Name3: | Seine River |
| Area Land Km2: | 10.26 |
| Population Footnotes: | [1] |
| Population Total: | 0 |
| Population As Of: | 2021 |
| Population Density Km2: | 0 |
| Website: | seineriverfirstnation.ca |
Seine River 23B is a First Nations reserve in northwestern Ontario, Canada. It is one of three reserves of the Seine River First Nation.