14 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Billings | 1 | 122,545 | 117,159 | 0.87% | 2,689 | 46 | City |
| Billings | 2 | 122,545 | 117,233 | 0.87% | 2,689 | 46 | City |
| Laurel | 3 | 7,258 | 7,222 | 0.1% | 2,786 | 3 | City |
| Laurel | 4 | 7,258 | 7,222 | 0.1% | 2,786 | 3 | City |
| Shepherd | 5 | 836 | 944 | 2.58% | 376 | 2 | CDP |
| Worden | 6 | 484 | 481 | -1.43% | 245 | 2 | CDP |
| Huntley | 7 | 364 | 522 | -1.36% | 239 | 2 | CDP |
| Ballantine | 8 | 260 | 352 | -1.52% | 286 | 1 | CDP |
| Nibbe | 9 | 161 | 120 | 7.33% | 694 | 0 | CDP |
| Custer | 10 | 143 | 151 | -0.69% | 454 | 0 | CDP |
| Broadview | 11 | 136 | 139 | -0.73% | 519 | 0 | Town |
| Broadview | 12 | 136 | 139 | -0.73% | 519 | 0 | Town |
| Acton | 13 | 99 | 76 | 7.61% | 413 | 0 | CDP |
| Pompeys Pillar | 14 | 29 | 86 | 7.41% | 149 | 0 | CDP |
Billings is the largest city in Yellowstone County, with a population of 122,545.
Pompeys Pillar is the smallest city in Yellowstone County, with a population of 29.
There are 14 cities in Yellowstone County, Montana.