24 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Delaware | 1 | 48,925 | 41,712 | 2.52% | 2,397 | 20 | City |
| Orange | 2 | 43,810 | 37,599 | 1.96% | 2,083 | 21 | Township |
| Westerville | 3 | 38,298 | 39,240 | -0.41% | 3,039 | 13 | City |
| Liberty | 4 | 34,459 | 33,252 | 0.41% | 1,051 | 33 | Township |
| Powell | 5 | 14,794 | 14,250 | 0.62% | 2,544 | 6 | City |
| Concord | 6 | 13,057 | 11,242 | 1.92% | 617 | 21 | Township |
| Sunbury | 7 | 11,195 | 6,725 | 7.13% | 1,567 | 7 | City |
| Berkshire | 8 | 6,245 | 5,403 | 1.74% | 297 | 21 | Township |
| Harlem | 9 | 5,341 | 4,578 | 1.97% | 201 | 27 | Township |
| Washington | 10 | 4,370 | 4,251 | 0.07% | 2,254 | 2 | Township |
| Scioto | 11 | 4,353 | 3,749 | 1.92% | 125 | 35 | Township |
| Delaware | 12 | 3,054 | 2,606 | 2.11% | 286 | 11 | Township |
| Porter | 13 | 2,489 | 2,144 | 1.92% | 98 | 25 | Township |
| Delaware | 14 | 2,055 | 2,011 | 0.64% | 58 | 35 | Township |
| Minerva Park | 15 | 1,936 | 2,010 | -0.62% | 2,992 | 1 | Village |
| Radnor | 16 | 1,832 | 1,579 | 1.89% | 59 | 31 | Township |
| Brown | 17 | 1,635 | 1,412 | 1.87% | 65 | 25 | Township |
| Ashley | 18 | 1,421 | 1,207 | 2.6% | 2,156 | 1 | Village |
| Ostrander | 19 | 1,291 | 1,098 | 2.54% | 1,376 | 1 | Village |
| Delaware | 20 | 1,242 | 1,237 | 0.16% | 40 | 31 | Township |
| Galena | 21 | 1,068 | 926 | 2.3% | 618 | 2 | Village |
| Shawnee Hills | 22 | 988 | 841 | 2.6% | 2,220 | 0 | Village |
| Hartford (Croton) | 23 | 416 | 407 | 0.48% | 779 | 1 | Village |
| Marlboro | 24 | 342 | 296 | 1.79% | 30 | 11 | Township |
Delaware is the largest city in Delaware County, with a population of 48,925.
Marlboro is the smallest city in Delaware County, with a population of 342.
There are 24 cities in Delaware County, Ohio.