| Una do Prelado River | |
| Pushpin Map: | Brazil |
| Source1 Location: | São Paulo |
| Mouth Location: | Atlantic ocean |
| Mouth Coordinates: | -24.4455°N -47.0792°W |
| Subdivision Type1: | Country |
| Subdivision Name1: | Brazil |
| Tributaries Left: | Cacunduva River |
The Una do Prelado River (Portuguese: Una do Prelado River) is a river in the state of São Paulo, Brazil.
The Una do Prelado River is the largest in the Juréia-Itatins Ecological Station, a strictly protected area of well-preserved Atlantic Forest created in 1986.It rises in the Banhado Grande region to the south-west of the Serra da Juréia, and meanders in a north-east direction parallel to the Atlantic coast for through a low plain between the Serra dos Itatins and the Serra da Juréia. Its main tributary is the Cacunduva River.
The final section in the east divides the Juréia-Itatins Ecological Station from the Itinguçu State Park, a conservation unit created in 2006.Near the sea the river separates into two branches which later recombine, enclosing the Ilha do Ameixal, which holds the Ilha do Ameixal Area of Relevant Ecological Interest.The Barra do Una lies at the river mouth, in the municipality of Peruíbe, the centre of the Barra do Una Sustainable Development Reserve.
The Una do Prelado River is a blackwater river fed by various streams from the north side of the Serra da Juréia and the Atlantic side of the Serra dos Itatins.The river is tidal for most of its length, with seawater reaching as far as from its mouth in dry periods.There are mangrove swamps up to from the estuary.