6 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Idaho Falls | 1 | 70,421 | 65,929 | 1.29% | 2,593 | 27 | City |
| Ammon | 2 | 20,649 | 17,876 | 2.76% | 2,526 | 8 | City |
| Iona | 3 | 3,203 | 2,751 | 2.89% | 2,544 | 1 | City |
| Ucon | 4 | 1,230 | 1,168 | 0.99% | 1,349 | 1 | City |
| Swan Valley | 5 | 327 | 240 | 5.48% | 28 | 12 | City |
| Irwin | 6 | 295 | 264 | 2.08% | 113 | 3 | City |
Idaho Falls is the largest city in Bonneville County, with a population of 70,421.
Irwin is the smallest city in Bonneville County, with a population of 295.
There are 6 cities in Bonneville County, Idaho.