27 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Delaware | 1 | 47,723 | 41,712 | 2.58% | 2,358 | 20 | City |
| Orange | 2 | 42,966 | 37,599 | 2% | 2,043 | 21 | Township |
| Westerville | 3 | 38,455 | 39,240 | -0.41% | 3,051 | 13 | City |
| Liberty | 4 | 34,320 | 33,252 | 0.41% | 1,047 | 33 | Township |
| Powell | 5 | 14,703 | 14,250 | 0.62% | 2,528 | 6 | City |
| Concord | 6 | 12,811 | 11,242 | 1.96% | 606 | 21 | Township |
| Sunbury | 7 | 10,450 | 6,725 | 7.68% | 2,171 | 5 | Village |
| Berkshire | 8 | 6,138 | 5,403 | 1.77% | 292 | 21 | Township |
| Harlem | 9 | 5,238 | 4,578 | 2.01% | 197 | 27 | Township |
| Washington | 10 | 4,367 | 4,251 | 0.07% | 2,252 | 2 | Township |
| Scioto | 11 | 4,271 | 3,749 | 1.96% | 123 | 35 | Township |
| Huber Ridge | 12 | 4,226 | 4,213 | -0.61% | 4,036 | 1 | CDP |
| Delaware | 13 | 2,991 | 2,606 | 2.15% | 280 | 11 | Township |
| Porter | 14 | 2,442 | 2,144 | 1.96% | 96 | 25 | Township |
| Delaware | 15 | 2,042 | 2,011 | 0.64% | 58 | 35 | Township |
| New California | 16 | 2,034 | 1,330 | 2.11% | 988 | 2 | CDP |
| Minerva Park | 17 | 1,948 | 2,010 | -0.66% | 3,011 | 1 | Village |
| Radnor | 18 | 1,798 | 1,579 | 1.93% | 58 | 31 | Township |
| Brown | 19 | 1,605 | 1,412 | 1.9% | 64 | 25 | Township |
| Ashley | 20 | 1,385 | 1,207 | 2.59% | 2,102 | 1 | Village |
| Ostrander | 21 | 1,259 | 1,098 | 2.61% | 1,342 | 1 | Village |
| Delaware | 22 | 1,240 | 1,237 | 0.16% | 40 | 31 | Township |
| Galena | 23 | 1,044 | 926 | 2.25% | 604 | 2 | Village |
| Shawnee Hills | 24 | 963 | 841 | 2.56% | 2,164 | 0 | Village |
| Hartford (Croton) | 25 | 414 | 407 | 0.24% | 775 | 1 | Village |
| Marlboro | 26 | 336 | 296 | 1.82% | 30 | 11 | Township |
| Radnor | 27 | 158 | 131 | -1.86% | 219 | 1 | CDP |
Delaware is the largest city in Delaware County, with a population of 47,723.
Radnor is the smallest city in Delaware County, with a population of 158.
There are 27 cities in Delaware County, Ohio.