20 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Mansfield | 1 | 47,627 | 47,525 | 0.04% | 1,543 | 31 | City |
| Shelby | 2 | 9,212 | 9,289 | -0.14% | 1,459 | 6 | City |
| Sharon | 3 | 8,930 | 9,011 | -0.17% | 371 | 24 | Township |
| Butler | 4 | 8,314 | 8,275 | 0.25% | 534 | 16 | Township |
| Butler | 5 | 6,704 | 6,658 | 0.4% | 203 | 33 | Township |
| Ontario | 6 | 6,638 | 6,668 | -0.08% | 599 | 11 | City |
| Washington | 7 | 6,563 | 6,609 | -0.14% | 205 | 32 | Township |
| Mifflin | 8 | 6,078 | 6,110 | -0.12% | 276 | 22 | Township |
| Butler | 9 | 3,442 | 3,559 | -0.43% | 105 | 33 | Township |
| Worthington | 10 | 2,977 | 2,991 | -0.13% | 83 | 36 | Township |
| Bellville | 11 | 2,012 | 1,960 | 0.45% | 706 | 3 | Village |
| Weller | 12 | 1,876 | 1,883 | -0.05% | 77 | 24 | Township |
| Cass | 13 | 1,601 | 1,612 | -0.06% | 62 | 26 | Township |
| Butler | 14 | 1,434 | 1,447 | 0% | 41 | 35 | Township |
| Bloominggrove | 15 | 1,283 | 1,291 | -0.16% | 51 | 25 | Township |
| Butler | 16 | 1,282 | 1,298 | -0.31% | 53 | 24 | Township |
| Butler | 17 | 1,181 | 1,182 | -0.17% | 46 | 25 | Township |
| Butler | 18 | 935 | 943 | -0.11% | 725 | 1 | Village |
| Shiloh | 19 | 610 | 616 | -0.16% | 666 | 1 | Village |
| Lucas | 20 | 584 | 589 | -0.17% | 863 | 1 | Village |
Mansfield is the largest city in Richland County, with a population of 47,627.
Lucas is the smallest city in Richland County, with a population of 584.
There are 20 cities in Richland County, Ohio.