There are 25 cities in Union County, Ohio.
Note: As defined by the US Census Bureau, a city's official boundaries often extend miles beyond the city itself and may even cross county lines. As such, several thousand US cities officially exist in two or more counties (and therefore appear on multiple counties' lists of cities.)
City | Rank | State | 2024 Population | 2020 Census | Annual Change | Density (mi²) | Area (mi²) |
|---|---|---|---|---|---|---|---|
| Columbus | 1 | Ohio | 909,676 | 906,266 | 0.09% | 4,121 | 220.72 |
| Dublin | 2 | Ohio | 48,654 | 49,342 | -0.35% | 1,971 | 24.68 |
| Delaware | 3 | Ohio | 46,099 | 41,691 | 2.45% | 2,278 | 20.24 |
| Hilliard | 4 | Ohio | 37,620 | 37,134 | 0.33% | 2,636 | 14.27 |
| Marion | 5 | Ohio | 34,646 | 36,008 | -0.97% | 2,672 | 12.96 |
| Marysville | 6 | Ohio | 28,607 | 25,707 | 2.6% | 1,758 | 16.28 |
| Plain City | 7 | Ohio | 4,515 | 4,145 | 2.1% | 1,642 | 2.75 |
| Richwood | 8 | Ohio | 2,559 | 2,235 | 3.27% | 2,060 | 1.24 |
| New California | 9 | Ohio | 1,891 | 1,330 | -0.47% | 919 | 2.06 |
| North Lewisburg | 10 | Ohio | 1,643 | 1,641 | 0.06% | 1,530 | 1.07 |
| Ostrander | 11 | Ohio | 1,236 | 1,100 | 2.83% | 1,318 | 0.94 |
| Prospect | 12 | Ohio | 1,043 | 1,069 | -0.57% | 1,441 | 0.72 |
| Milford Center | 13 | Ohio | 926 | 810 | 3.23% | 2,194 | 0.42 |
| West Mansfield | 14 | Ohio | 742 | 754 | -0.4% | 892 | 0.83 |
| Mount Victory | 15 | Ohio | 587 | 603 | -0.68% | 695 | 0.84 |
| East Liberty | 16 | Ohio | 418 | 390 | 1.7% | 265 | 1.58 |
| New Bloomington | 17 | Ohio | 411 | 413 | 0% | 934 | 0.44 |
| Waldo | 18 | Ohio | 317 | 321 | -0.31% | 489 | 0.65 |
| Ridgeway | 19 | Ohio | 304 | 312 | -0.65% | 537 | 0.57 |
| Green Camp | 20 | Ohio | 301 | 309 | -0.66% | 891 | 0.34 |
| Magnetic Springs | 21 | Ohio | 300 | 260 | 3.45% | 1,408 | 0.21 |
| Woodstock | 22 | Ohio | 283 | 291 | -0.7% | 1,000 | 0.28 |
| Unionville Center | 23 | Ohio | 229 | 239 | -0.87% | 1,449 | 0.16 |
| Raymond | 24 | Ohio | 155 | 155 | 0% | 122 | 1.27 |
| Kilbourne | 25 | Ohio | 17 | 14 | -19.05% | 38 | 0.45 |
Note: City markers shown outside the county boundary mean that a part of the city extends into this county, but is primarily located in an adjacent county.
Columbus is the largest city in Union County.
Kilbourne is the smallest city in Union County.
There are 25 cities in Union County, Ohio.