The Liard River is a river that flows through the Yukon Territory, British Columbia and the Northwest Territories, and in Canada. It is 1,215 km (755 miles) long. It begins in the southeast of the Yukon Territory in the Pelly Mountains. It flows southeast into northern British Columbia, passes through the main range of the Rocky Mountains and then flows northeast through dense forests into the Mackenzie River at Fort Simpson, Fort Smith Region in the Northwest Territories. The South Nahanni and Fort Nelson rivers are its chief tributaries. It is navigable to Fort Liard, 165 miles from its mouth.

The area around the river in the Yukon Territory is called the Liard River Valley.

The Alaska Highway follows the river for part of its route.