24 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Thief River Falls | 1 | 8,811 | 8,836 | -0.06% | 1,468 | 6 | City |
| Rocksbury township | 2 | 1,031 | 1,092 | -0.77% | 31 | 33.48 | Township |
| North township | 3 | 607 | 645 | -0.82% | 27 | 22.71 | Township |
| Smiley township | 4 | 580 | 620 | -0.85% | 16 | 36.01 | Township |
| Norden township | 5 | 367 | 368 | 0.55% | 13 | 27.57 | Township |
| Sanders township | 6 | 286 | 298 | -0.69% | 8 | 36.17 | Township |
| St. Hilaire | 7 | 248 | 273 | -1.98% | 317 | 0.78 | City |
| Highlanding township | 8 | 188 | 199 | -0.53% | 5 | 36.10 | Township |
| River Falls township | 9 | 179 | 190 | -0.56% | 8 | 22.65 | Township |
| Silverton township | 10 | 172 | 185 | -1.15% | 6 | 26.66 | Township |
| Kratka township | 11 | 134 | 142 | -0.74% | 4 | 35.94 | Township |
| Deer Park township | 12 | 119 | 127 | -0.83% | 5 | 23.06 | Township |
| Goodridge | 13 | 105 | 110 | -0.94% | 559 | 0.19 | City |
| Numedal township | 14 | 96 | 96 | 1.05% | 3 | 27.82 | Township |
| Star township | 15 | 96 | 100 | 0% | 3 | 36.13 | Township |
| Reiner township | 16 | 90 | 97 | -1.1% | 3 | 26.89 | Township |
| Wyandotte township | 17 | 87 | 94 | -1.14% | 4 | 22.64 | Township |
| Cloverleaf township | 18 | 85 | 92 | -1.16% | 3 | 26.92 | Township |
| Goodridge township | 19 | 74 | 78 | 0% | 3 | 26.88 | Township |
| Hickory township | 20 | 63 | 69 | -1.56% | 2 | 35.11 | Township |
| Black River township | 21 | 62 | 68 | -1.59% | 3 | 23.96 | Township |
| Polk Centre township | 22 | 61 | 64 | 0% | 3 | 24.09 | Township |
| Bray township | 23 | 48 | 53 | -2.04% | 1 | 35.87 | Township |
| Mayfield township | 24 | 45 | 47 | 0% | 2 | 22.91 | Township |
Thief River Falls is the largest city in Pennington County, with a population of 8,811.
Mayfield township is the smallest city in Pennington County.
There are 24 cities in Pennington County, Minnesota.