The Little Bighorn River is a tributary of the Bighorn River in the United States in the states of Wyoming and Montana. The river is somewhat infamous as the site of the Battle of the Little Bighorn in 1876.
The Little Bighorn rises in extreme northern Wyoming, along the north side of the Bighorn Mountains. It flows northward into Montana and across the Crow Indian Reservation, past the towns of Wyola, Lodge Grass and Crow Agency, and joins the Bighorn near the town of Hardin.
The battle site, which is on the grounds of Little Bighorn Battlefield National Monument, is approximately five miles south of Crow Agency, along the eastern side of the river.