21 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Clarion | 1 | 4,541 | 3,926 | 2.78% | 2,885 | 1.57 | Borough |
| Clarion township | 2 | 3,521 | 3,641 | -0.79% | 113 | 31.27 | Township |
| Limestone township | 3 | 1,947 | 1,967 | -0.1% | 58 | 33.62 | Township |
| Limestone township | 4 | 1,796 | 1,869 | -0.88% | 47 | 37.83 | Township |
| Limestone township | 5 | 1,733 | 1,745 | -0.29% | 84 | 20.55 | Township |
| Paint township | 6 | 1,588 | 1,643 | -0.81% | 78 | 20.33 | Township |
| Monroe township | 7 | 1,467 | 1,494 | -0.27% | 50 | 29.45 | Township |
| Elk township | 8 | 1,376 | 1,432 | -0.86% | 44 | 31.46 | Township |
| Redbank township | 9 | 1,287 | 1,327 | -0.54% | 43 | 30.05 | Township |
| Porter township | 10 | 1,227 | 1,284 | -1.05% | 28 | 43.88 | Township |
| Knox | 11 | 1,062 | 1,097 | -0.66% | 1,890 | 0.56 | Borough |
| New Bethlehem | 12 | 938 | 975 | -0.74% | 2,013 | 0.47 | Borough |
| Rimersburg | 13 | 904 | 941 | -0.77% | 2,484 | 0.36 | Borough |
| East Brady | 14 | 793 | 818 | -0.63% | 980 | 0.81 | Borough |
| Sligo | 15 | 665 | 685 | -0.6% | 473 | 1.41 | Borough |
| Strattanville | 16 | 516 | 538 | -0.77% | 1,032 | 0.50 | Borough |
| Hawthorn | 17 | 462 | 477 | -0.65% | 451 | 1.02 | Borough |
| Shippenville | 18 | 432 | 442 | -0.46% | 1,113 | 0.39 | Borough |
| St. Petersburg | 19 | 327 | 339 | -0.61% | 1,025 | 0.32 | Borough |
| Foxburg | 20 | 176 | 180 | -0.56% | 478 | 0.37 | Borough |
| Callensburg | 21 | 142 | 147 | -0.7% | 979 | 0.14 | Borough |
Clarion is the largest city in Clarion County, with a population of 4,541.
Callensburg is the smallest city in Clarion County.
There are 21 cities in Clarion County, Pennsylvania.