19 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Rockland city | 1 | 7,087 | 6,948 | 0.4% | 552 | 12.85 | City |
| Rockland | 2 | 7,086 | 6,948 | 0.4% | 551 | 12.85 | City |
| Camden town | 3 | 5,110 | 5,233 | -1.1% | 280 | 18.24 | Town |
| Warren town | 4 | 4,950 | 4,880 | 0.08% | 107 | 46.47 | Town |
| Rockport town | 5 | 3,614 | 3,651 | -0.88% | 167 | 21.64 | Town |
| Thomaston town | 6 | 2,708 | 2,740 | -0.88% | 248 | 10.93 | Town |
| St. George town | 7 | 2,570 | 2,597 | -0.77% | 103 | 25.02 | Town |
| Union town | 8 | 2,453 | 2,383 | 0.29% | 76 | 32.15 | Town |
| Hope town | 9 | 1,710 | 1,699 | -0.64% | 78 | 21.96 | Town |
| Washington town | 10 | 1,546 | 1,595 | -1.28% | 41 | 38.04 | Town |
| South Thomaston town | 11 | 1,498 | 1,513 | -1.12% | 131 | 11.43 | Town |
| Owls Head town | 12 | 1,478 | 1,501 | -1% | 166 | 8.88 | Town |
| Cushing town | 13 | 1,461 | 1,501 | -1.15% | 76 | 19.23 | Town |
| Appleton town | 14 | 1,451 | 1,412 | 0.14% | 44 | 32.71 | Town |
| Vinalhaven town | 15 | 1,235 | 1,287 | -1.44% | 53 | 23.45 | Town |
| Friendship town | 16 | 1,131 | 1,145 | -0.88% | 80 | 14.11 | Town |
| North Haven town | 17 | 423 | 419 | -0.24% | 36 | 11.62 | Town |
| Isle au Haut town | 18 | 88 | 88 | 0% | 7 | 12.52 | Town |
| Matinicus Isle plantation | 19 | 49 | 51 | -2% | 20 | 2.40 | Plantation |
Rockland city is the largest city in Knox County, with a population of 7,087.
Matinicus Isle plantation is the smallest city in Knox County.
There are 19 cities in Knox County, Maine.