7 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Idaho Falls | 1 | 69,398 | 65,905 | 1.02% | 2,612 | 26.57 | City |
| Ammon | 2 | 20,778 | 17,875 | 2.88% | 2,580 | 8.05 | City |
| Lincoln | 3 | 3,636 | 3,380 | 0% | 2,338 | 1.55 | CDP |
| Iona | 4 | 3,345 | 2,745 | 3.72% | 2,657 | 1.26 | City |
| Ucon | 5 | 1,280 | 1,167 | 1.83% | 1,404 | 0.91 | City |
| Swan Valley | 6 | 343 | 242 | 6.19% | 30 | 11.61 | City |
| Irwin | 7 | 301 | 263 | 2.73% | 115 | 2.61 | City |
Idaho Falls is the largest city in Bonneville County, with a population of 69,398.
Irwin is the smallest city in Bonneville County.
There are 7 cities in Bonneville County, Idaho.