8 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Fairmont | 1 | 17,975 | 18,414 | -0.49% | 2,090 | 9 | City |
| Mannington | 2 | 1,898 | 1,953 | -0.58% | 1,737 | 1 | City |
| Barrackville | 3 | 1,193 | 1,212 | -0.33% | 1,731 | 1 | Town |
| Rivesville | 4 | 803 | 825 | -0.62% | 1,532 | 1 | Town |
| Grant Town | 5 | 665 | 685 | -0.6% | 1,262 | 1 | Town |
| Farmington | 6 | 394 | 386 | 0.25% | 949 | 0 | Town |
| Fairview | 7 | 368 | 372 | -0.27% | 1,314 | 0 | Town |
| Worthington | 8 | 172 | 176 | -0.58% | 295 | 1 | Town |
Fairmont is the largest city in Marion County, with a population of 17,975.
Worthington is the smallest city in Marion County, with a population of 172.
There are 8 cities in Marion County, West Virginia.