There are several rivers named Black River in the province of Ontario, Canada.

The Black River in Hastings County, Ontario joins the Moira River near Tweed, Ontario.

The Black River in York Regional Municipality, Ontario originates in the Oak Ridges Moraine and flows north to empty into Lake Simcoe. Agriculture is the most important use of the land in this river's watershed.

The Black River in Simcoe County, Ontario flows south and west from the Muskoka Region south of the Lake of Bays to empties into Lake Couchiching. This river is used for recreational canoeing and kayaking. The Head River is a tributary of this river.

The Black River in Cochrane District, Ontario is a tributary of the Abitibi River.

The Black River in Thunder Bay District, Ontario flows from headwaters near Manitouwadge, Ontario to join the Pic River near its mouth on Lake Superior south of the town of Marathon, Ontario. There is a small hydroelectric plant on the river operated by the Pic River First Nation. Because, at one time, there were two competing lumber companies in the area, an elevated timber slide was built to divert one company's logs from the Black River over the Pic River, which was used to transport the logs of the other company.

See also

• List of Ontario rivers