8 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Fairmont | 1 | 17,887 | 18,414 | -0.49% | 2,079 | 9 | City |
| Mannington | 2 | 1,887 | 1,953 | -0.58% | 1,726 | 1 | City |
| Barrackville | 3 | 1,189 | 1,212 | -0.34% | 1,726 | 1 | Town |
| Rivesville | 4 | 799 | 825 | -0.5% | 1,525 | 1 | Town |
| Grant Town | 5 | 661 | 685 | -0.6% | 1,254 | 1 | Town |
| Farmington | 6 | 396 | 386 | 0.51% | 954 | 0 | Town |
| Fairview | 7 | 367 | 372 | -0.27% | 1,311 | 0 | Town |
| Worthington | 8 | 171 | 176 | -0.58% | 293 | 1 | Town |
Fairmont is the largest city in Marion County, with a population of 17,887.
Worthington is the smallest city in Marion County, with a population of 171.
There are 8 cities in Marion County, West Virginia.