16 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| West Frankfort | 1 | 7,073 | 7,253 | -0.51% | 1,419 | 4.98 | City |
| Benton | 2 | 6,533 | 6,695 | -0.49% | 1,190 | 5.49 | City |
| Christopher | 3 | 2,605 | 2,684 | -0.61% | 1,606 | 1.62 | City |
| McLeansboro | 4 | 2,587 | 2,644 | -0.42% | 943 | 2.74 | City |
| Sesser | 5 | 1,838 | 1,885 | -0.49% | 1,784 | 1.03 | City |
| Zeigler | 6 | 1,458 | 1,482 | -0.34% | 1,073 | 1.36 | City |
| Royalton | 7 | 1,031 | 1,061 | -0.58% | 925 | 1.11 | Village |
| West City | 8 | 633 | 652 | -0.63% | 394 | 1.61 | Village |
| Valier | 9 | 537 | 557 | -0.74% | 478 | 1.12 | Village |
| North City | 10 | 497 | 509 | -0.4% | 229 | 2.17 | Village |
| Thompsonville | 11 | 476 | 485 | -0.42% | 234 | 2.03 | Village |
| Buckner | 12 | 395 | 405 | -0.5% | 453 | 0.87 | Village |
| Orient | 13 | 317 | 327 | -0.63% | 426 | 0.74 | City |
| Hanaford | 14 | 312 | 319 | -0.32% | 310 | 1.01 | Village |
| Ewing | 15 | 292 | 299 | -0.34% | 289 | 1.01 | Village |
| Mulkeytown | 16 | 55 | 128 | -12.7% | 200 | 0.28 | CDP |
West Frankfort is the largest city in Franklin County, with a population of 7,073.
Mulkeytown is the smallest city in Franklin County.
There are 16 cities in Franklin County, Illinois.