26 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Milford | 1 | 14,608 | 11,310 | 4.73% | 1,482 | 9.86 | City |
| Seaford | 2 | 9,231 | 7,991 | 2.76% | 1,809 | 5.10 | City |
| Georgetown | 3 | 8,332 | 7,184 | 2.84% | 1,659 | 5.02 | Town |
| Millsboro | 4 | 8,099 | 6,943 | 2.94% | 1,585 | 5.11 | Town |
| Laurel | 5 | 4,529 | 3,894 | 2.89% | 1,635 | 2.77 | Town |
| Milton | 6 | 3,897 | 3,342 | 2.93% | 2,096 | 1.86 | Town |
| Lewes | 7 | 3,794 | 3,319 | 2.57% | 905 | 4.19 | City |
| Selbyville | 8 | 3,374 | 2,898 | 2.9% | 940 | 3.59 | Town |
| Long Neck | 9 | 3,234 | 2,869 | 2.67% | 1,172 | 2.76 | CDP |
| Ocean View | 10 | 3,120 | 2,662 | 3.04% | 1,124 | 2.78 | Town |
| Bridgeville | 11 | 2,999 | 2,574 | 2.92% | 622 | 4.82 | Town |
| Delmar | 12 | 2,334 | 2,038 | 2.59% | 1,228 | 1.90 | Town |
| Millville | 13 | 2,177 | 1,857 | 3.03% | 855 | 2.55 | Town |
| Lincoln | 14 | 1,799 | 605 | 7.15% | 638 | 2.82 | CDP |
| Blades | 15 | 1,372 | 1,179 | 2.93% | 2,481 | 0.55 | Town |
| Rehoboth Beach | 16 | 1,292 | 1,112 | 2.87% | 1,100 | 1.18 | City |
| Greenwood | 17 | 1,153 | 992 | 2.85% | 1,452 | 0.79 | Town |
| Bethany Beach | 18 | 1,123 | 962 | 2.93% | 978 | 1.15 | Town |
| Dagsboro | 19 | 1,019 | 874 | 2.93% | 709 | 1.44 | Town |
| Frankford | 20 | 929 | 801 | 2.88% | 1,266 | 0.73 | Town |
| Ellendale | 21 | 573 | 493 | 2.87% | 1,348 | 0.42 | Town |
| South Bethany | 22 | 534 | 458 | 2.89% | 1,062 | 0.50 | Town |
| Dewey Beach | 23 | 417 | 357 | 2.96% | 1,260 | 0.33 | Town |
| Fenwick Island | 24 | 398 | 342 | 2.84% | 1,202 | 0.33 | Town |
| Bethel | 25 | 273 | 238 | 2.63% | 620 | 0.44 | Town |
| Henlopen Acres | 26 | 161 | 138 | 3.21% | 631 | 0.26 | Town |
Milford is the largest city in Sussex County, with a population of 14,608.
Henlopen Acres is the smallest city in Sussex County.
There are 26 cities in Sussex County, Delaware.