| Piranhas River | |
| Source1 Location: | Tocantins state |
| Mouth: | Araguaia River |
| Subdivision Type1: | Country |
| Subdivision Name1: | Brazil |
The Piranhas River is a river of Tocantins state in central Brazil. The Piranhas joins the Araguaia River in the west-central area of Tocantins state near the municipality of Araguacema.