22 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Wausau | 1 | 40,317 | 40,042 | 0.14% | 2,097 | 19 | City |
| Weston | 2 | 15,899 | 15,733 | 0.21% | 735 | 22 | Village |
| Kronenwetter | 3 | 8,450 | 8,372 | 0.18% | 164 | 52 | Village |
| Rib Mountain | 4 | 7,268 | 7,301 | 17.78% | 296 | 25 | Village |
| Rib Mountain | 5 | 7,268 | 7,301 | -0.1% | 296 | 25 | Village |
| Rib Mountain | 6 | 6,208 | 7,301 | 0.6% | 253 | 25 | Village |
| Rib Mountain | 7 | 6,208 | 7,301 | -14.67% | 253 | 25 | Village |
| Rothschild | 8 | 5,647 | 5,557 | 0.32% | 865 | 7 | Village |
| Mosinee | 9 | 4,549 | 4,459 | 0.4% | 579 | 8 | City |
| Maine | 10 | 2,616 | 2,606 | 0.08% | 61 | 43 | Village |
| Schofield | 11 | 2,325 | 2,154 | 1.48% | 1,099 | 2 | City |
| Spencer | 12 | 1,810 | 1,825 | -0.17% | 919 | 2 | Village |
| Stratford | 13 | 1,621 | 1,584 | 0.43% | 306 | 5 | Village |
| Marathon City | 14 | 1,544 | 1,578 | -0.45% | 473 | 3 | Village |
| Edgar | 15 | 1,426 | 1,443 | -0.28% | 789 | 2 | Village |
| Athens | 16 | 1,063 | 1,065 | -0.09% | 434 | 2 | Village |
| Hatley | 17 | 656 | 651 | 0.15% | 672 | 1 | Village |
| Unity | 18 | 377 | 387 | -0.53% | 380 | 1 | Village |
| Aniwa | 19 | 231 | 245 | -1.28% | 109 | 2 | Village |
| Eland | 20 | 187 | 196 | -1.06% | 85 | 2 | Village |
| Elderon | 21 | 155 | 162 | -1.27% | 138 | 1 | Village |
| Fenwood | 22 | 136 | 140 | -0.73% | 138 | 1 | Village |
Wausau is the largest city in Marathon County, with a population of 40,317.
Fenwood is the smallest city in Marathon County, with a population of 136.
There are 22 cities in Marathon County, Wisconsin.