5 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Key West | 1 | 24,680 | 26,360 | -1.12% | 4,408 | 6 | City |
| Marathon | 2 | 10,130 | 9,857 | 0.46% | 1,199 | 8 | City |
| Islamorada, Village of Islands | 3 | 6,958 | 7,122 | -0.39% | 1,078 | 6 | Village |
| Key Colony Beach | 4 | 730 | 786 | -1.22% | 1,659 | 0 | City |
| Layton | 5 | 204 | 216 | -0.97% | 1,259 | 0 | City |
Key West is the largest city in Monroe County, with a population of 24,680.
Layton is the smallest city in Monroe County, with a population of 204.
There are 5 cities in Monroe County, Florida.