| Cajari River | |
| Pushpin Map: | Brazil |
| Source1 Location: | Marajó island |
| Mouth Location: | Afuá, Pará |
| Mouth Coordinates: | -0.1636°N -50.4004°W |
| Subdivision Type1: | Country |
| Subdivision Name1: | Brazil |
The Cajari River (Portuguese: Rio Cajari) is a river in Amazon River delta in the state of Pará, Brazil.
The Cajari River is in the northeast of the island of Marajó in the delta region where the Amazon and Tocantins rivers empty into the Atlantic Ocean.It is contained within the Marajó Archipelago Environmental Protection Area, a sustainable use conservation unit created in 1989 to protect the Marajó island and surrounding islands.The river runs to the east of the Charapucu State Park into the Baía do Vieira Grande, one of the mouths of the Amazon.The Furo Charapucu channel runs to the south of the park, connecting the Cajari River to another part of the Vieira Grande Bay.