27 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Vandalia | 1 | 7,294 | 7,453 | -0.44% | 895 | 8.15 | City |
| Vandalia township | 2 | 6,153 | 6,334 | -0.57% | 175 | 35.08 | Township |
| Sharon township | 3 | 2,982 | 3,012 | -0.17% | 120 | 24.77 | Township |
| Avena township | 4 | 1,876 | 1,933 | -0.64% | 52 | 36.32 | Township |
| Ramsey township | 5 | 1,603 | 1,653 | -0.62% | 29 | 54.37 | Township |
| Otego township | 6 | 1,395 | 1,431 | -0.57% | 39 | 35.34 | Township |
| St. Elmo | 7 | 1,230 | 1,267 | -0.57% | 829 | 1.48 | City |
| Ramsey | 8 | 883 | 912 | -0.67% | 795 | 1.11 | Village |
| La Clede township | 9 | 849 | 874 | -0.59% | 23 | 36.80 | Township |
| Loudon township | 10 | 847 | 871 | -0.59% | 14 | 59.80 | Township |
| Brownstown | 11 | 673 | 693 | -0.59% | 882 | 0.76 | Village |
| Lone Grove township | 12 | 607 | 623 | -0.49% | 16 | 36.86 | Township |
| Sefton township | 13 | 556 | 567 | -0.54% | 11 | 49.88 | Township |
| Kaskaskia township | 14 | 523 | 538 | -0.57% | 15 | 34.30 | Township |
| Farina | 15 | 522 | 542 | -0.76% | 358 | 1.46 | Village |
| Bear Grove township | 16 | 519 | 536 | -0.57% | 14 | 37.35 | Township |
| Wheatland township | 17 | 488 | 503 | -0.61% | 13 | 36.69 | Township |
| Seminary township | 18 | 482 | 488 | -0.21% | 11 | 44.92 | Township |
| Wilberton township | 19 | 476 | 488 | -0.42% | 13 | 35.53 | Township |
| Shafter township | 20 | 451 | 465 | -0.66% | 13 | 35.59 | Township |
| Bowling Green township | 21 | 411 | 422 | -0.48% | 16 | 25.53 | Township |
| St. Peter | 22 | 313 | 322 | -0.63% | 601 | 0.52 | Village |
| Pope township | 23 | 221 | 221 | 0.45% | 9 | 25.42 | Township |
| Hurricane township | 24 | 210 | 218 | -0.94% | 8 | 27.02 | Township |
| South Hurricane township | 25 | 202 | 208 | -0.49% | 7 | 27.06 | Township |
| Carson township | 26 | 101 | 105 | -0.98% | 6 | 17.80 | Township |
| Bingham | 27 | 59 | 61 | 0% | 215 | 0.27 | Village |
Vandalia is the largest city in Fayette County, with a population of 7,294.
Bingham is the smallest city in Fayette County.
There are 27 cities in Fayette County, Illinois.