23 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Bethany | 1 | 3,337 | 3,318 | 0.03% | 93 | 36 | Township |
| Bethany | 2 | 2,932 | 2,909 | 0.17% | 660 | 4 | City |
| Colfax | 3 | 588 | 580 | 0.17% | 14 | 43 | Township |
| Sugar Creek | 4 | 456 | 452 | 0% | 15 | 30 | Township |
| White Oak | 5 | 455 | 451 | 0.22% | 13 | 36 | Township |
| Grant | 6 | 385 | 385 | -0.26% | 11 | 34 | Township |
| Ridgeway | 7 | 379 | 376 | 0.26% | 311 | 1 | City |
| Marion | 8 | 365 | 361 | 0.27% | 10 | 35 | Township |
| Gilman City | 9 | 332 | 331 | 0% | 395 | 1 | City |
| Jefferson | 10 | 324 | 327 | -0.61% | 9 | 36 | Township |
| Cainsville | 11 | 283 | 282 | 0% | 206 | 1 | City |
| Eagleville | 12 | 281 | 280 | 0% | 278 | 1 | Town |
| New Hampton | 13 | 228 | 225 | 0.44% | 415 | 1 | City |
| Dallas | 14 | 217 | 215 | 0% | 6 | 36 | Township |
| Blythedale | 15 | 215 | 212 | 0.47% | 700 | 0 | Village |
| Trail Creek | 16 | 194 | 192 | 0% | 5 | 36 | Township |
| Sherman | 17 | 193 | 191 | 0% | 6 | 35 | Township |
| Cypress | 18 | 164 | 160 | 0.61% | 5 | 30 | Township |
| Adams | 19 | 133 | 132 | 0% | 4 | 30 | Township |
| Fox Creek | 20 | 101 | 100 | 0% | 3 | 36 | Township |
| Mount Moriah | 21 | 77 | 76 | 0% | 75 | 1 | Town |
| Clay | 22 | 64 | 63 | 0% | 1 | 44 | Township |
| Irena | 23 | 12 | 12 | 0% | 14 | 1 | Village |
Bethany is the largest city in Harrison County, with a population of 3,337.
Irena is the smallest city in Harrison County, with a population of 12.
There are 23 cities in Harrison County, Missouri.