Nanih Waiya, which has also been spelled Nunih Waya, is an ancient platform earthworks mound in southern Winston County, Mississippi, and is believed to have been constructed by indigenous people during the Middle Woodland period, about 300 to 600 CE. Nanih Waiya is a Choctaw native American name meaning leaning hill.

This large rectangular platform mound measures 25 feet high, 218 feet long, and 140 feet wide and is located within in a state park. A small burial mound, now nearly leveled by plowing, is located outside the park boundaries several hundred yards away. A long, raised embankment once enclosed the site. Most of this earthen enclosure has been destroyed by cultivation, but a short segment remains along the edge of a swamp to the northwest of the large mound.

Since the 17th century, the Choctaw and Chickasaw have venerated Nanih Waiya mound and a nearby cave as their sacred origin location.