21 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Sanford | 1 | 68,374 | 61,077 | 2.17% | 2,853 | 24 | City |
| Sanford | 2 | 68,374 | 61,098 | 2.17% | 2,853 | 24 | City |
| Altamonte Springs | 3 | 47,533 | 46,254 | 0.58% | 5,212 | 9 | City |
| Altamonte Springs | 4 | 47,533 | 46,172 | 0.58% | 5,212 | 9 | City |
| Oviedo | 5 | 42,373 | 40,059 | 1.13% | 2,728 | 16 | City |
| Oviedo | 6 | 42,373 | 40,012 | 1.13% | 2,728 | 16 | City |
| Winter Springs | 7 | 40,182 | 38,357 | 0.9% | 2,704 | 15 | City |
| Winter Springs | 8 | 40,182 | 38,382 | 0.9% | 2,704 | 15 | City |
| Casselberry | 9 | 32,327 | 28,775 | 2.14% | 4,639 | 7 | City |
| Casselberry | 10 | 32,327 | 28,940 | 2.14% | 4,639 | 7 | City |
| Wekiwa Springs | 11 | 24,838 | 24,008 | 0.77% | 2,892 | 9 | CDP |
| Longwood | 12 | 17,506 | 15,097 | 2.44% | 3,170 | 6 | City |
| Longwood | 13 | 17,506 | 15,421 | 2.44% | 3,170 | 6 | City |
| Lake Mary | 14 | 17,027 | 16,833 | 0.22% | 1,876 | 9 | City |
| Lake Mary | 15 | 17,027 | 16,836 | 0.22% | 1,876 | 9 | City |
| Goldenrod | 16 | 12,610 | 12,341 | 0.3% | 4,996 | 3 | CDP |
| Fern Park | 17 | 8,333 | 8,665 | 0.51% | 4,156 | 2 | CDP |
| Heathrow | 18 | 7,381 | 6,898 | 1.36% | 2,691 | 3 | CDP |
| Geneva | 19 | 3,324 | 3,164 | 0.79% | 261 | 13 | CDP |
| Chuluota | 20 | 2,484 | 1,939 | 0% | 1,216 | 2 | CDP |
| Black Hammock | 21 | 1,139 | 1,080 | 0% | 102 | 11 | CDP |
Sanford is the largest city in Seminole County, with a population of 68,374.
Black Hammock is the smallest city in Seminole County, with a population of 1,139.
There are 21 cities in Seminole County, Florida.