17 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Vincennes | 1 | 21,503 | 21,869 | -0.41% | 358 | 60 | Township |
| Vincennes | 2 | 16,443 | 16,758 | -0.38% | 2,206 | 7 | City |
| Vigo | 3 | 4,012 | 4,078 | -0.57% | 61 | 66 | Township |
| Bicknell | 4 | 2,990 | 3,033 | -0.3% | 2,210 | 1 | City |
| Harrison | 5 | 1,903 | 1,919 | -0.37% | 24 | 79 | Township |
| Busseron | 6 | 1,259 | 1,261 | -0.24% | 24 | 52 | Township |
| Johnson | 7 | 1,245 | 1,259 | -0.4% | 25 | 50 | Township |
| Widner | 8 | 1,078 | 1,094 | -0.55% | 26 | 41 | Township |
| Steen | 9 | 806 | 814 | -0.25% | 22 | 37 | Township |
| Oaktown | 10 | 580 | 580 | 0% | 2,132 | 0 | Town |
| Monroe City | 11 | 488 | 492 | -0.2% | 1,814 | 0 | Town |
| Bruceville | 12 | 449 | 447 | 0% | 1,309 | 0 | Town |
| Wheatland | 13 | 391 | 393 | -0.26% | 954 | 0 | Town |
| Sandborn | 14 | 359 | 362 | -0.28% | 921 | 0 | Town |
| Edwardsport | 15 | 279 | 283 | -0.36% | 993 | 0 | Town |
| Decker | 16 | 211 | 215 | -0.94% | 5 | 44 | Township |
| Decker | 17 | 198 | 198 | 0% | 1,053 | 0 | Town |
Vincennes is the largest city in Knox County, with a population of 21,503.
Decker is the smallest city in Knox County, with a population of 198.
There are 17 cities in Knox County, Indiana.