| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Clarion | 1 | 4,067 | 3,925 | 0.74% | 2,584 | 2 | Borough |
| Clarion | 2 | 3,574 | 3,661 | -0.25% | 114 | 31 | Township |
| Limestone | 3 | 1,949 | 1,965 | -0.15% | 58 | 34 | Township |
| Limestone | 4 | 1,819 | 1,872 | -0.33% | 48 | 38 | Township |
| Limestone | 5 | 1,738 | 1,749 | -0.06% | 85 | 21 | Township |
| Paint | 6 | 1,622 | 1,645 | 0% | 80 | 20 | Township |
| Monroe | 7 | 1,469 | 1,481 | 0% | 50 | 29 | Township |
| Elk | 8 | 1,401 | 1,429 | 0.14% | 45 | 31 | Township |
| Redbank | 9 | 1,298 | 1,332 | -0.23% | 43 | 30 | Township |
| Porter | 10 | 1,251 | 1,288 | -0.16% | 29 | 44 | Township |
| Knox | 11 | 1,061 | 1,097 | -0.66% | 1,888 | 1 | Borough |
| Limestone | 12 | 993 | 1,009 | -0.1% | 74 | 13 | Township |
| Knox | 13 | 977 | 993 | 0% | 61 | 16 | Township |
| Knox | 14 | 976 | 1,007 | -0.31% | 31 | 31 | Township |
| Toby | 15 | 966 | 990 | -0.21% | 33 | 29 | Township |
| New Bethlehem | 16 | 936 | 969 | -0.74% | 2,009 | 0 | Borough |
| Rimersburg | 17 | 913 | 947 | -0.65% | 2,508 | 0 | Borough |
| Perry | 18 | 890 | 918 | -0.34% | 31 | 29 | Township |
| Salem | 19 | 880 | 897 | -0.23% | 55 | 16 | Township |
| East Brady | 20 | 795 | 818 | -0.5% | 983 | 1 | Borough |
| Sligo | 21 | 663 | 678 | -0.45% | 471 | 1 | Borough |
| Knox | 22 | 579 | 598 | -0.34% | 22 | 26 | Township |
| Licking | 23 | 575 | 571 | 0.17% | 33 | 18 | Township |
| Highland | 24 | 544 | 533 | 0.74% | 27 | 20 | Township |
| Strattanville | 25 | 518 | 532 | -0.58% | 1,036 | 1 | Borough |
| Hawthorn | 26 | 466 | 477 | -0.43% | 455 | 1 | Borough |
| Shippenville | 27 | 439 | 442 | -0.23% | 1,131 | 0 | Borough |
| Piney | 28 | 405 | 408 | 0.25% | 23 | 18 | Township |
| Millcreek | 29 | 361 | 362 | 0% | 12 | 29 | Township |
| St. Petersburg | 30 | 324 | 337 | -0.61% | 1,016 | 0 | Borough |
| Limestone | 31 | 296 | 310 | -0.67% | 9.0 | 31 | Township |
| Foxburg | 32 | 177 | 181 | -0.56% | 481 | 0 | Borough |
| Callensburg | 33 | 142 | 147 | -0.7% | 979 | 0 | Borough |
| Brady | 34 | 70 | 72 | 0% | 42 | 2 | Township |
Clarion is the largest city in Clarion County, with a population of 4,067.
Brady is the smallest city in Clarion County, with a population of 70.
There are 34 cities in Clarion County, Pennsylvania.