Belize River is a river located in Belize - it drains more than one-quarter of the country as it winds along the northern edge of the Maya Mountains across the center of the country to the sea near Belize City. Also known as the Old River, the Belize River is navigable up to the Guatemalan border and served as the main artery of commerce and communication between the interior and the coast until well into the twentieth century.

It flows through Belize river valley which largely comprises of tropical rain forest areas. The river has long been associated with forestry and mahogany extraction, which still occurs.