27 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Vandalia | 1 | 7,309 | 7,456 | -0.33% | 897 | 8 | City |
| Vandalia | 2 | 6,182 | 6,333 | -0.29% | 176 | 35 | Township |
| Sharon | 3 | 2,994 | 3,008 | -0.07% | 121 | 25 | Township |
| Avena | 4 | 1,885 | 1,930 | -0.32% | 52 | 36 | Township |
| Ramsey | 5 | 1,611 | 1,654 | -0.37% | 30 | 54 | Township |
| Otego | 6 | 1,403 | 1,431 | -0.21% | 40 | 35 | Township |
| St. Elmo | 7 | 1,231 | 1,267 | -0.49% | 830 | 1 | City |
| Ramsey | 8 | 886 | 913 | -0.45% | 797 | 1 | Village |
| Loudon | 9 | 855 | 872 | -0.23% | 14 | 60 | Township |
| La Clede | 10 | 853 | 874 | -0.23% | 23 | 37 | Township |
| Brownstown | 11 | 672 | 693 | -0.44% | 881 | 1 | Village |
| Lone Grove | 12 | 610 | 625 | -0.33% | 17 | 37 | Township |
| Sefton | 13 | 561 | 568 | -0.18% | 11 | 50 | Township |
| Kaskaskia | 14 | 535 | 546 | -0.19% | 16 | 34 | Township |
| Farina | 15 | 525 | 542 | -0.57% | 360 | 1 | Village |
| Bear Grove | 16 | 521 | 534 | -0.19% | 14 | 37 | Township |
| Wheatland | 17 | 481 | 498 | -0.62% | 13 | 37 | Township |
| Seminary | 18 | 479 | 487 | -0.21% | 11 | 45 | Township |
| Wilberton | 19 | 478 | 486 | -0.21% | 13 | 36 | Township |
| Shafter | 20 | 455 | 465 | -0.22% | 13 | 36 | Township |
| Bowling Green | 21 | 413 | 422 | 0% | 16 | 26 | Township |
| St. Peter | 22 | 308 | 320 | -0.65% | 591 | 1 | Village |
| Pope | 23 | 215 | 221 | -0.46% | 8 | 25 | Township |
| Hurricane | 24 | 212 | 218 | -0.47% | 8 | 27 | Township |
| South Hurricane | 25 | 205 | 208 | 0% | 8 | 27 | Township |
| Carson | 26 | 105 | 105 | 0% | 6 | 18 | Township |
| Bingham | 27 | 60 | 62 | 0% | 219 | 0 | Village |
Vandalia is the largest city in Fayette County, with a population of 7,309.
Bingham is the smallest city in Fayette County, with a population of 60.
There are 27 cities in Fayette County, Illinois.