The Nishnabotna River is a tributary of the Missouri River in southwestern Iowa, northwestern Missouri and southeastern Nebraska in the United States. It flows for most of its length as two parallel streams in Iowa, the East Nishnabotna River and the West Nishnabotna River. The east and west branches are each about 120 miles (190 km) long; from their confluence the Nishnabotna flows approximately another 16 miles (26 km).
Several sections of the rivers' courses have been straightened and heavily channelized.
The name "Nishnabotna" comes from an Otoe (Chiwere) word meaning "canoe-making river."
The East Nishnabotna rises in southwestern Carroll County and flows generally south-southwestwardly through Audubon, Cass, Pottawattamie, Montgomery, Page and Fremont Counties, past the towns of Exira, Brayton, Atlantic, Lewis, Elliott, Shenandoah, Red Oak and Riverton.
The West Nishnabotna River rises in southwestern Carroll County and also flows generally south-southwestwardly through Crawford, Shelby, Pottawattamie, Mills and Fremont Counties, past the towns of Manning, Irwin, Kirkman, Harlan, Avoca, Hancock, Oakland and Carson. At Harlan it collects the West Fork West Nishnabotna River, which rises in southwestern Carroll County and flows southwestwardly through Crawford and Shelby Counties, past Manilla and Defiance. Near Avoca it collects the East Branch West Nishnabotna River, which rises in southwestern Carroll County and flows southwestwardly through Audubon, Shelby and Pottawattamie Counties, past Gray. The West Nishnabotna was the topic of a humorous song on the 1974 C.W. McCall albums Wolf Creek Pass and Rubber Duck.