18 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Rockland | 1 | 7,034 | 6,949 | -0.18% | 547 | 13 | City |
| Warren | 2 | 5,332 | 4,885 | 2.62% | 115 | 46 | Town |
| Camden | 3 | 5,131 | 5,237 | -0.56% | 281 | 18 | Town |
| Rockport | 4 | 3,601 | 3,645 | -0.72% | 166 | 22 | Town |
| Thomaston | 5 | 2,725 | 2,740 | -0.47% | 249 | 11 | Town |
| St. George | 6 | 2,548 | 2,597 | -0.86% | 102 | 25 | Town |
| Union | 7 | 2,419 | 2,384 | -0.37% | 75 | 32 | Town |
| Hope | 8 | 1,704 | 1,701 | -0.64% | 78 | 22 | Town |
| Washington | 9 | 1,542 | 1,594 | -0.96% | 41 | 38 | Town |
| South Thomaston | 10 | 1,498 | 1,513 | -0.86% | 131 | 11 | Town |
| Owls Head | 11 | 1,471 | 1,508 | -1.08% | 166 | 9 | Town |
| Appleton | 12 | 1,458 | 1,413 | 0.21% | 45 | 33 | Town |
| Cushing | 13 | 1,455 | 1,501 | -0.95% | 76 | 19 | Town |
| Vinalhaven | 14 | 1,231 | 1,288 | -1.12% | 52 | 23 | Town |
| Friendship | 15 | 1,150 | 1,144 | -0.09% | 81 | 14 | Town |
| North Haven | 16 | 416 | 418 | -0.95% | 36 | 12 | Town |
| Isle au Haut | 17 | 83 | 86 | -1.19% | 7 | 13 | Town |
| Matinicus Isle | 18 | 48 | 51 | -2.04% | 20 | 2 | Plantation |
Rockland is the largest city in Knox County, with a population of 7,034.
Matinicus Isle is the smallest city in Knox County, with a population of 48.
There are 18 cities in Knox County, Maine.