5 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Key West | 1 | 24,960 | 26,360 | -1.11% | 4,458 | 6 | City |
| Marathon | 2 | 10,084 | 9,857 | 0.45% | 1,194 | 8 | City |
| Islamorada, Village of Islands | 3 | 6,985 | 7,122 | -0.4% | 1,083 | 6 | Village |
| Key Colony Beach | 4 | 739 | 786 | -1.34% | 1,680 | 0 | City |
| Layton | 5 | 206 | 216 | -0.96% | 1,272 | 0 | City |
Key West is the largest city in Monroe County, with a population of 24,960.
Layton is the smallest city in Monroe County, with a population of 206.
There are 5 cities in Monroe County, Florida.