21 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Mahnomen | 1 | 1,191 | 1,238 | -0.75% | 1,138 | 1.05 | City |
| Pembina township | 2 | 622 | 657 | -1.58% | 17 | 36.33 | Township |
| Naytahwaush | 3 | 446 | 476 | -1.76% | 154 | 2.90 | CDP |
| Island Lake township | 4 | 303 | 311 | -0.66% | 9 | 34.41 | Township |
| Little Elbow township | 5 | 279 | 288 | -1.06% | 9 | 31.32 | Township |
| Oakland township | 6 | 251 | 262 | -1.18% | 8 | 32.57 | Township |
| Mahnomen | 7 | 178 | 215 | -2.2% | 140 | 1.27 | CDP |
| Lake Grove township | 8 | 173 | 180 | -1.14% | 5 | 35.15 | Township |
| La Garde township | 9 | 164 | 168 | -0.61% | 5 | 33.66 | Township |
| Chief township | 10 | 150 | 157 | -1.32% | 4 | 34.77 | Township |
| Heier township | 11 | 136 | 140 | -0.73% | 4 | 33.75 | Township |
| Marsh Creek township | 12 | 136 | 140 | -0.73% | 4 | 37.74 | Township |
| Clover township | 13 | 130 | 134 | -0.76% | 4 | 34.88 | Township |
| Popple Grove township | 14 | 114 | 118 | -0.87% | 3 | 37.27 | Township |
| Rosedale township | 15 | 109 | 115 | -1.8% | 3 | 35.13 | Township |
| Beaulieu township | 16 | 95 | 99 | -1.04% | 3 | 33.70 | Township |
| Lengby | 17 | 87 | 91 | -1.14% | 354 | 0.25 | City |
| Bejou | 18 | 80 | 84 | -1.23% | 279 | 0.29 | City |
| Bejou township | 19 | 66 | 70 | -1.49% | 2 | 37.37 | Township |
| Gregory township | 20 | 58 | 59 | 0% | 2 | 35.16 | Township |
| Pine Bend | 21 | 35 | 51 | 6.06% | 28 | 1.26 | CDP |
Mahnomen is the largest city in Mahnomen County, with a population of 1,191.
Pine Bend is the smallest city in Mahnomen County.
There are 21 cities in Mahnomen County, Minnesota.