27 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Delaware | 1 | 47,455 | 41,712 | 2.48% | 2,345 | 20.24 | City |
| Orange township | 2 | 43,262 | 37,596 | 2.58% | 2,057 | 21.03 | Township |
| Westerville | 3 | 37,100 | 39,244 | -1.14% | 2,944 | 12.60 | City |
| Liberty township | 4 | 34,290 | 33,250 | 0.62% | 1,046 | 32.78 | Township |
| Powell | 5 | 14,651 | 14,250 | 0.55% | 2,520 | 5.82 | City |
| Concord township | 6 | 12,890 | 11,242 | 2.5% | 609 | 21.15 | Township |
| Sunbury | 7 | 9,422 | 6,717 | 6.09% | 1,957 | 4.81 | Village |
| Berkshire township | 8 | 6,213 | 5,413 | 2.52% | 296 | 21 | Township |
| Harlem township | 9 | 5,272 | 4,578 | 2.61% | 199 | 26.56 | Township |
| Washington township | 10 | 4,386 | 4,251 | 0.55% | 2,262 | 1.94 | Township |
| Scioto township | 11 | 4,300 | 3,750 | 2.5% | 124 | 34.82 | Township |
| Huber Ridge | 12 | 4,226 | 4,213 | -0.61% | 4,036 | 1.05 | CDP |
| Delaware township | 13 | 3,015 | 2,610 | 2.69% | 282 | 10.68 | Township |
| Porter township | 14 | 2,459 | 2,143 | 2.54% | 97 | 25.36 | Township |
| New California | 15 | 2,034 | 1,330 | 2.11% | 988 | 2.06 | CDP |
| Delaware township | 16 | 2,031 | 2,011 | 0.54% | 57 | 35.47 | Township |
| Minerva Park | 17 | 1,900 | 2,010 | -1.14% | 2,937 | 0.65 | Village |
| Radnor township | 18 | 1,816 | 1,579 | 2.6% | 58 | 31.06 | Township |
| Brown township | 19 | 1,623 | 1,415 | 2.53% | 65 | 25.14 | Township |
| Ashley | 20 | 1,392 | 1,207 | 2.73% | 2,112 | 0.66 | Village |
| Ostrander | 21 | 1,262 | 1,099 | 2.69% | 1,345 | 0.94 | Village |
| Delaware township | 22 | 1,230 | 1,237 | 0% | 40 | 31.13 | Township |
| Galena | 23 | 1,074 | 934 | 2.68% | 621 | 1.73 | Village |
| Shawnee Hills | 24 | 965 | 840 | 2.66% | 2,169 | 0.45 | Village |
| Hartford (Croton) | 25 | 406 | 401 | 0.25% | 760 | 0.53 | Village |
| Marlboro township | 26 | 339 | 296 | 2.42% | 30 | 11.28 | Township |
| Radnor | 27 | 158 | 131 | -1.86% | 219 | 0.72 | CDP |
Delaware is the largest city in Delaware County, with a population of 47,455.
Radnor is the smallest city in Delaware County.
There are 27 cities in Delaware County, Ohio.