34 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Clarion | 1 | 4,194 | 3,926 | 1.28% | 2,665 | 2 | Borough |
| Clarion | 2 | 3,554 | 3,641 | -0.45% | 114 | 31 | Township |
| Limestone | 3 | 1,960 | 1,967 | 0% | 58 | 34 | Township |
| Limestone | 4 | 1,823 | 1,870 | -0.33% | 48 | 38 | Township |
| Limestone | 5 | 1,734 | 1,748 | -0.57% | 84 | 21 | Township |
| Paint | 6 | 1,615 | 1,646 | -0.31% | 79 | 20 | Township |
| Monroe | 7 | 1,481 | 1,492 | 0% | 50 | 29 | Township |
| Elk | 8 | 1,393 | 1,431 | -0.36% | 44 | 31 | Township |
| Redbank | 9 | 1,296 | 1,328 | -0.38% | 43 | 30 | Township |
| Porter | 10 | 1,250 | 1,285 | -0.4% | 28 | 44 | Township |
| Knox | 11 | 1,068 | 1,097 | -0.56% | 1,900 | 1 | Borough |
| Limestone | 12 | 1,009 | 1,012 | 0% | 76 | 13 | Township |
| Knox | 13 | 982 | 992 | 0.31% | 61 | 16 | Township |
| Knox | 14 | 976 | 1,010 | -0.71% | 31 | 31 | Township |
| Toby | 15 | 959 | 981 | -0.31% | 33 | 29 | Township |
| New Bethlehem | 16 | 948 | 975 | -0.63% | 2,034 | 0 | Borough |
| Rimersburg | 17 | 923 | 950 | -0.65% | 2,536 | 0 | Borough |
| Perry | 18 | 897 | 920 | -0.33% | 31 | 29 | Township |
| Salem | 19 | 882 | 898 | -0.34% | 55 | 16 | Township |
| East Brady | 20 | 800 | 818 | -0.5% | 989 | 1 | Borough |
| Sligo | 21 | 668 | 680 | -0.45% | 475 | 1 | Borough |
| Knox | 22 | 577 | 596 | -0.52% | 22 | 26 | Township |
| Licking | 23 | 574 | 573 | 0% | 33 | 18 | Township |
| Highland | 24 | 533 | 532 | -0.37% | 27 | 20 | Township |
| Strattanville | 25 | 520 | 538 | -0.76% | 1,040 | 1 | Borough |
| Hawthorn | 26 | 466 | 479 | -0.64% | 455 | 1 | Borough |
| Shippenville | 27 | 442 | 444 | -0.23% | 1,139 | 0 | Borough |
| Piney | 28 | 397 | 401 | 0.25% | 22 | 18 | Township |
| Millcreek | 29 | 366 | 361 | 1.1% | 13 | 29 | Township |
| St. Petersburg | 30 | 328 | 337 | -0.61% | 1,028 | 0 | Borough |
| Limestone | 31 | 295 | 310 | -1.34% | 9 | 31 | Township |
| Foxburg | 32 | 179 | 182 | -0.56% | 486 | 0 | Borough |
| Callensburg | 33 | 139 | 146 | -1.42% | 959 | 0 | Borough |
| Brady | 34 | 72 | 75 | -1.37% | 44 | 2 | Township |
Clarion is the largest city in Clarion County, with a population of 4,194.
Brady is the smallest city in Clarion County, with a population of 72.
There are 34 cities in Clarion County, Pennsylvania.