19 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Rockland | 1 | 7,087 | 6,949 | 0.38% | 552 | 13 | City |
| Rockland | 2 | 7,047 | 6,949 | -0.18% | 548 | 13 | City |
| Warren | 3 | 5,196 | 4,885 | 2.69% | 112 | 46 | Town |
| Camden | 4 | 5,160 | 5,237 | -0.56% | 283 | 18 | Town |
| Rockport | 5 | 3,627 | 3,645 | -0.71% | 168 | 22 | Town |
| Thomaston | 6 | 2,738 | 2,740 | -0.47% | 251 | 11 | Town |
| St. George | 7 | 2,570 | 2,597 | -0.85% | 103 | 25 | Town |
| Union | 8 | 2,428 | 2,384 | -0.37% | 76 | 32 | Town |
| Hope | 9 | 1,715 | 1,701 | -0.64% | 78 | 22 | Town |
| Washington | 10 | 1,557 | 1,594 | -0.95% | 41 | 38 | Town |
| South Thomaston | 11 | 1,511 | 1,513 | -0.85% | 132 | 11 | Town |
| Owls Head | 12 | 1,487 | 1,508 | -1.06% | 168 | 9 | Town |
| Cushing | 13 | 1,469 | 1,501 | -0.94% | 76 | 19 | Town |
| Appleton | 14 | 1,455 | 1,413 | 0.21% | 44 | 33 | Town |
| Vinalhaven | 15 | 1,245 | 1,288 | -1.11% | 53 | 23 | Town |
| Friendship | 16 | 1,151 | 1,144 | -0.09% | 82 | 14 | Town |
| North Haven | 17 | 420 | 418 | -0.94% | 36 | 12 | Town |
| Isle au Haut | 18 | 84 | 86 | -1.18% | 7 | 13 | Town |
| Matinicus Isle | 19 | 49 | 51 | -2% | 20 | 2 | Plantation |
Rockland is the largest city in Knox County, with a population of 7,087.
Matinicus Isle is the smallest city in Knox County, with a population of 49.
There are 19 cities in Knox County, Maine.