Walnut
- County:
- Pottawattamie County
- County Seat:
- No
- Area (mi²):
- 2.198
- State:
- Iowa
Walnut is a city located in Pottawattamie County, Iowa. Walnut has a 2026 population of 728. Walnut is currently declining at a rate of -0.14% annually and its population has decreased by -2.02% since the most recent census, which recorded a population of 743 in 2020.