| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Key West | 1 | 24,809 | 26,364 | -0.76% | 4,431 | 6 | City |
| Marathon | 2 | 10,139 | 9,863 | 0.79% | 1,200 | 8 | City |
| Islamorada, Village of Islands | 3 | 6,951 | 7,119 | -0.06% | 1,077 | 6 | Village |
| Key Colony Beach | 4 | 734 | 787 | -0.94% | 1,668 | 0 | City |
| Layton | 5 | 208 | 215 | -0.48% | 1,284 | 0 | City |
Key West is the largest city in Monroe County, with a population of 24,809.
Layton is the smallest city in Monroe County, with a population of 208.
There are 5 cities in Monroe County, Florida.