14 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Bluefield | 1 | 9,044 | 9,639 | -1.23% | 1,008 | 9 | City |
| Bluefield | 2 | 9,044 | 9,608 | -1.23% | 1,008 | 9 | City |
| Princeton | 3 | 5,528 | 5,879 | -1.2% | 1,834 | 3 | City |
| Princeton | 4 | 5,528 | 5,860 | -1.2% | 1,834 | 3 | City |
| Bluewell | 5 | 2,415 | 2,740 | 0.63% | 537 | 4 | CDP |
| Athens | 6 | 1,169 | 1,214 | -0.76% | 2,901 | 0 | Town |
| Athens | 7 | 1,169 | 1,211 | -0.76% | 2,901 | 0 | Town |
| Brush Fork | 8 | 1,138 | 1,025 | -0.35% | 599 | 2 | CDP |
| Lashmeet | 9 | 760 | 473 | 2.43% | 1,013 | 1 | CDP |
| Montcalm | 10 | 711 | 582 | -0.14% | 260 | 3 | CDP |
| Bramwell | 11 | 260 | 275 | -1.14% | 468 | 1 | Town |
| Bramwell | 12 | 260 | 274 | -1.14% | 468 | 1 | Town |
| Oakvale | 13 | 129 | 133 | -0.77% | 309 | 0 | Town |
| Oakvale | 14 | 129 | 133 | -0.77% | 309 | 0 | Town |
Bluefield is the largest city in Mercer County, with a population of 9,044.
Oakvale is the smallest city in Mercer County, with a population of 129.
There are 14 cities in Mercer County, West Virginia.