库尤尼河是南美洲的河流，属于埃塞奎博河的支流，发源自委内瑞拉的圭亚那地盾，最终注入马扎鲁尼河，河道全长618公里，流域面积50,347平方公里。

The Cuyuni River is a South American river and a tributary of the Essequibo River. It rises in the Guiana Highlands of Venezuela where it descends northward to El Dorado, and turns eastward to meander through the tropical rain forests of Guayana Esequiba. It finally turns southeastward, flowing to its confluence with the Mazaruni River. The Cuyuni River marks the limit of the disputed territory of Guayana Esequiba for approximately 100 kilometres (62 mi).