| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Delaware | 1 | 47,579 | 41,684 | 2.02% | 2,331 | 20 | City |
| Westerville | 2 | 37,948 | 39,236 | -0.57% | 3,011 | 13 | City |
| Powell | 3 | 19,001 | 14,257 | 4.01% | 3,268 | 6 | City |
| Sunbury | 4 | 9,263 | 6,735 | 4.58% | 1,297 | 7 | City |
| Minerva Park | 5 | 1,937 | 2,010 | -0.67% | 2,994 | 1 | Village |
| Ashley | 6 | 1,371 | 1,206 | 2.08% | 2,080 | 1 | Village |
| Ostrander | 7 | 1,243 | 1,099 | 1.97% | 1,325 | 1 | Village |
| Galena | 8 | 1,037 | 932 | 1.77% | 600 | 2 | Village |
| Shawnee Hills | 9 | 950 | 841 | 2.04% | 2,135 | 0 | Village |
| Hartford (Croton) | 10 | 414 | 409 | 0.24% | 775 | 1 | Village |
Delaware is the largest city in Delaware County, with a population of 47,579.
Hartford (Croton) is the smallest city in Delaware County, with a population of 414.
There are 10 cities in Delaware County, Ohio.