| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Augusta | 1 | 19,130 | 18,932 | -0.13% | 347 | 55 | City |
| Waterville | 2 | 17,696 | 16,687 | 0.67% | 1,308 | 14 | City |
| Winslow | 3 | 8,042 | 7,965 | -0.26% | 218 | 37 | Town |
| Oakland | 4 | 6,350 | 6,244 | -0.17% | 247 | 26 | Town |
| Gardiner | 5 | 6,246 | 5,978 | 0.64% | 398 | 16 | City |
| Winthrop | 6 | 6,151 | 6,134 | -0.11% | 197 | 31 | Town |
| Sidney | 7 | 4,964 | 4,658 | 0.71% | 117 | 42 | Town |
| China | 8 | 4,654 | 4,419 | 0.39% | 93 | 50 | Town |
| Vassalboro | 9 | 4,653 | 4,528 | 0.13% | 105 | 44 | Town |
| Monmouth | 10 | 4,269 | 4,086 | 0.4% | 126 | 34 | Town |
| Litchfield | 11 | 3,824 | 3,596 | 0.71% | 102 | 37 | Town |
| West Gardiner | 12 | 3,664 | 3,671 | -0.38% | 149 | 25 | Town |
| Belgrade | 13 | 3,570 | 3,251 | 0.82% | 83 | 43 | Town |
| Pittston | 14 | 3,515 | 2,894 | 2.84% | 109 | 32 | Town |
| Clinton | 15 | 3,367 | 3,371 | -0.33% | 77 | 44 | Town |
| Farmingdale | 16 | 2,991 | 2,994 | -0.3% | 266 | 11 | Town |
| Chelsea | 17 | 2,844 | 2,779 | -0.14% | 146 | 20 | Town |
| Benton | 18 | 2,826 | 2,721 | 0.18% | 99 | 28 | Town |
| Windsor | 19 | 2,771 | 2,640 | 0.47% | 80 | 35 | Town |
| Readfield | 20 | 2,748 | 2,605 | 0.66% | 94 | 29 | Town |
| Hallowell | 21 | 2,633 | 2,566 | 0.34% | 449 | 6 | City |
| Manchester | 22 | 2,490 | 2,460 | -0.08% | 116 | 21 | Town |
| Albion | 23 | 2,092 | 2,013 | 0% | 54 | 39 | Town |
| Mount Vernon | 24 | 1,875 | 1,727 | 1.74% | 49 | 38 | Town |
| Randolph | 25 | 1,782 | 1,747 | 0.11% | 835 | 2 | Town |
| Fayette | 26 | 1,297 | 1,165 | 1.57% | 44 | 29 | Town |
| Rome | 27 | 1,186 | 1,149 | 0.17% | 47 | 25 | Town |
| Wayne | 28 | 1,175 | 1,131 | 0.69% | 61 | 19 | Town |
| Vienna | 29 | 619 | 583 | 0.65% | 25 | 24 | Town |
Augusta is the largest city in Kennebec County, with a population of 19,130.
Vienna is the smallest city in Kennebec County, with a population of 619.
There are 29 cities in Kennebec County, Maine.