The Bighorn Mountains are shown highlighted in red in the western United States

The Bighorn Mountains are a mountain range in northern Wyoming in the United States, forming a spur from the Rocky Mountains extending approximately 200 miles (320 km) northward on the Great Plains. They are separated from the Absaroka Range, which lie on the main branch of the Rockies in western Wyoming, by the Bighorn Basin.

The range is the location of the headwaters of the Little Bighorn, Tongue, and Powder rivers.

The highest peaks of the range include Cloud Peak (13,167 ft) and Black Tooth Mountain (13,005 ft).