| Ji-Paraná River | |
| Name Other: | Machado River |
| Map Size: | 300 |
| Pushpin Map: | Amazon river watershed |
| Pushpin Map Size: | 300 |
| Pushpin Map Caption: | Location of the mouth of the Ji-Paraná River in the Amazonas watershed |
| Subdivision Type1: | Country |
| Subdivision Name1: | Brazil |
| Length: | [1] |
| Discharge1 Location: | Confluence of Madeira, Rondônia |
| Discharge1 Avg: | 2100m3/s |
| Discharge1 Max: | [2] |
| Source1 Location: | Confluence of Pimenta Bueno and Comemoração, Parecis plateau, Rondônia, Brazil |
| Mouth: | Madeira River |
| Mouth Location: | Rondônia, Brazil |
| Mouth Coordinates: | -8.0486°N -62.8974°W |
| Progression: | Madeira → Amazon → Atlantic Ocean |
| River System: | Amazon |
| Tributaries Left: | Pimenta Bueno, Jaru, Rolim de Moura, Muqui, Urupá, Machadinho, Juruazinho, Preto |
| Tributaries Right: | Comemoração, São João |
The Ji-Paraná River (Machado River), sometimes spelled Jiparaná, is a river in Rondônia state in western Brazil. It is a tributary of the Madeira River in the Amazon Basin. For much of its length it runs roughly parallel with the northeastern state border of Rondônia. The city of Ji-Paraná is divided by the river.
Part of the river's basin is covered by the Jacundá National Forest, a sustainable use conservation unit.Part of the basin is in the Jaru Biological Reserve, a fully protected conservation unit created in 1984.The river forms the southern boundary in Rondônia of the Campos Amazônicos National Park, a protected area created in 2006 that holds an unusual enclave of cerrado vegetation in the Amazon rainforest.