| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Fairmont | 1 | 17,953 | 18,426 | -0.45% | 2,087 | 9 | City |
| Mannington | 2 | 1,899 | 1,956 | -0.58% | 1,737 | 1 | City |
| Barrackville | 3 | 1,192 | 1,211 | -0.33% | 1,730 | 1 | Town |
| Rivesville | 4 | 802 | 825 | -0.5% | 1,531 | 1 | Town |
| Grant Town | 5 | 665 | 685 | -0.6% | 1,262 | 1 | Town |
| Farmington | 6 | 397 | 389 | 0.51% | 957 | 0 | Town |
| Fairview | 7 | 366 | 372 | -0.27% | 1,307 | 0 | Town |
| Worthington | 8 | 170 | 175 | -0.58% | 292 | 1 | Town |
Fairmont is the largest city in Marion County, with a population of 17,953.
Worthington is the smallest city in Marion County, with a population of 170.
There are 8 cities in Marion County, West Virginia.