The Opeongo River is a river in Nipissing District, Ontario, Canada.

It flows south and east from the east arm of Opeongo Lake in Algonquin Park to joining the Madawaska River at Bark Lake to empty into the Ottawa River.

The river is used for recreational canoeing and kayaking. Much of the river outside of Algonquin has been designated a provincial waterway park.

See also

• List of Ontario rivers