Note: As defined by the US Census Bureau, a city's official boundaries often extend miles beyond the city itself and may even cross county lines. As such, several thousand US cities officially exist in two or more counties (and therefore appear on multiple counties' lists of cities.)
City | Rank | 2024 Pop. | 2020 Pop. | Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Key West | 1 | 24,684 | 26,360 | -1.67% | 4,409 | 5.6 | City |
| Key Largo | 2 | 12,286 | 9,670 | 1.09% | 1,020 | 12.0 | CDP |
| Marathon | 3 | 9,847 | 9,855 | -0.02% | 1,166 | 8.4 | City |
| Islamorada, Village Islands | 4 | 6,943 | 7,122 | -0.64% | 1,077 | 6.4 | Village |
| Stock Island | 5 | 4,672 | 4,692 | 1.17% | 5,582 | 0.8 | CDP |
| Big Pine Key | 6 | 4,544 | 4,853 | 0.46% | 445 | 10.2 | CDP |
| Big Coppitt Key | 7 | 3,310 | 2,644 | 1.88% | 2,868 | 1.2 | CDP |
| Cudjoe Key | 8 | 2,317 | 2,157 | 1.71% | 448 | 5.2 | CDP |
| Tavernier | 9 | 2,282 | 1,980 | 0.48% | 908 | 2.5 | CDP |
| North Key Largo | 10 | 1,276 | 884 | 0.24% | 69 | 18.6 | CDP |
| Duck Key | 11 | 749 | 761 | 1.22% | 1,250 | 0.6 | CDP |
| Key Colony Beach | 12 | 745 | 787 | -1.46% | 1,693 | 0.4 | City |
| Layton | 13 | 199 | 211 | -1.49% | 1,228 | 0.2 | City |
Note: City markers shown outside the county boundary mean that a part of the city extends into this county, but is primarily located in an adjacent county.
Key West is the largest city in Monroe County.
Layton is the smallest city in Monroe County.
There are 13 cities in Monroe County, Florida.