| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Fairmont | 1 | 10,032 | 10,444 | -0.66% | 669 | 15 | City |
| Truman | 2 | 1,051 | 1,098 | -0.76% | 956 | 1 | City |
| Sherburn | 3 | 1,036 | 1,058 | -0.38% | 1,127 | 1 | City |
| Welcome | 4 | 683 | 709 | -0.58% | 469 | 1 | City |
| Trimont | 5 | 676 | 709 | -0.88% | 860 | 1 | City |
| Ceylon | 6 | 290 | 305 | -1.02% | 561 | 1 | City |
| Granada | 7 | 276 | 289 | -0.72% | 483 | 1 | City |
| Northrop | 8 | 214 | 225 | -0.93% | 1,634 | 0 | City |
| Dunnell | 9 | 130 | 132 | -0.76% | 850 | 0 | City |
| Ormsby | 10 | 122 | 119 | 0% | 346 | 0 | City |
Fairmont is the largest city in Martin County, with a population of 10,032.
Ormsby is the smallest city in Martin County, with a population of 122.
There are 10 cities in Martin County, Minnesota.