6 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Idaho Falls | 1 | 71,320 | 65,929 | 1.28% | 2,626 | 27 | City |
| Ammon | 2 | 21,204 | 17,876 | 2.69% | 2,594 | 8 | City |
| Iona | 3 | 3,294 | 2,751 | 2.84% | 2,616 | 1 | City |
| Ucon | 4 | 1,243 | 1,168 | 1.06% | 1,363 | 1 | City |
| Swan Valley | 5 | 345 | 240 | 5.5% | 30 | 12 | City |
| Irwin | 6 | 301 | 264 | 2.03% | 115 | 3 | City |
Idaho Falls is the largest city in Bonneville County, with a population of 71,320.
Irwin is the smallest city in Bonneville County, with a population of 301.
There are 6 cities in Bonneville County, Idaho.