10 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Oakleaf Plantation | 1 | 31,502 | 28,153 | 2.42% | 1,918 | 16.42 | CDP |
| Lakeside | 2 | 30,980 | 31,058 | 0.01% | 2,303 | 13.45 | CDP |
| Fleming Island | 3 | 30,481 | 30,582 | 0.74% | 1,925 | 15.84 | CDP |
| Bellair-Meadowbrook Terrace | 4 | 13,977 | 15,168 | 0.31% | 3,407 | 4.10 | CDP |
| Asbury Lake | 5 | 13,469 | 10,842 | 2.42% | 794 | 16.96 | CDP |
| Middleburg | 6 | 11,546 | 12,544 | -0.83% | 589 | 19.62 | CDP |
| Green Cove Springs | 7 | 10,305 | 9,867 | 0.86% | 1,225 | 8.41 | City |
| Orange Park | 8 | 9,047 | 9,089 | -0.09% | 2,487 | 3.64 | Town |
| Keystone Heights | 9 | 1,596 | 1,446 | 1.92% | 1,485 | 1.07 | City |
| Penney Farms | 10 | 848 | 823 | 0.59% | 581 | 1.46 | Town |
Oakleaf Plantation is the largest city in Clay County, with a population of 31,502.
Penney Farms is the smallest city in Clay County.
There are 10 cities in Clay County, Florida.