The Rio Cubatãozinho is a river in the state of Paraná in southern Brazil, with a total course of approximately 60 kilometers. It originates in the Serra das Canavieiras, in the mountainous region between the municipalities of Guaratuba and Morretes, and flows until it joins the Cubatão River at coordinates 25°52′S 48°43′W.

The river's headwaters lie within the Guaricana National Park, a protected area of 49,287 hectares established in 2014 that encompasses a mountainous section of Atlantic Forest. Along its course, the left bank borders the Lagoa do Parado Municipal Nature Park, a protected area of marshland noted for its biodiversity. These conservation areas give the river a largely natural setting through much of its length.

The river is navigable by canoe as far as Porto Limeira, which serves as a practical upstream limit for paddling. Several tributaries feed into the Cubatãozinho along its course, including the Ribeirão da Prata, Rio dos Henriques, Guarajuva, Canavieiras, Parado, Furta Maré, and Rasgado.