| Pacajá River | |
| Pushpin Map: | Brazil |
| Pushpin Map Caption: | Mouth location in Brazil |
| River System: | Pará River |
| Source1 Location: | Pará state |
| Mouth Coordinates: | -1.9996°N -50.8546°W |
| Subdivision Type1: | Country |
| Subdivision Name1: | Brazil |
The Pacajá River (Portuguese: Rio Pacajá) is a river of Pará state in north-central Brazil.It is a tributary of the Pará River, a channel that connects the Amazon and Tocantins rivers to the south of Marajó island.
The basin of the Pacajá River is in the Xingu–Tocantins–Araguaia moist forests ecoregion.