| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Marion | 1 | 12,199 | 11,275 | 1.23% | 350 | 35 | Township |
| Leroy | 2 | 3,926 | 3,792 | 1.16% | 115 | 34 | Township |
| Leroy | 3 | 3,679 | 3,658 | -0.03% | 102 | 36 | Township |
| Reed City | 4 | 2,541 | 2,484 | 0.51% | 1,209 | 2 | City |
| Hersey | 5 | 2,011 | 1,954 | -0.1% | 57 | 35 | Township |
| Evart | 6 | 1,799 | 1,753 | 0.56% | 730 | 2 | City |
| Marion | 7 | 1,647 | 1,658 | -0.36% | 64 | 26 | Township |
| Marion | 8 | 1,600 | 1,567 | -0.19% | 43 | 37 | Township |
| Marion | 9 | 1,540 | 1,568 | -0.45% | 43 | 36 | Township |
| Rose Lake | 10 | 1,461 | 1,406 | 0% | 43 | 34 | Township |
| Burdell | 11 | 1,443 | 1,409 | -0.21% | 39 | 37 | Township |
| Evart | 12 | 1,364 | 1,329 | -0.15% | 42 | 33 | Township |
| Le Roy | 13 | 1,289 | 1,253 | -0.15% | 37 | 35 | Township |
| Sylvan | 14 | 1,012 | 981 | 0% | 29 | 35 | Township |
| Sherman | 15 | 1,006 | 986 | -0.4% | 27 | 37 | Township |
| Osceola | 16 | 978 | 951 | -0.2% | 29 | 34 | Township |
| Marion | 17 | 806 | 785 | 0.5% | 626 | 1 | Village |
| Middle Branch | 18 | 793 | 774 | -0.38% | 22 | 35 | Township |
| Marion | 19 | 778 | 763 | 0.65% | 32 | 24 | Township |
| Orient | 20 | 743 | 726 | -0.4% | 21 | 35 | Township |
| Hartwick | 21 | 591 | 579 | -0.34% | 17 | 35 | Township |
| Hersey | 22 | 364 | 352 | 0.55% | 331 | 1 | Village |
| Tustin | 23 | 250 | 246 | 0.4% | 644 | 0 | Village |
Marion is the largest city in Osceola County, with a population of 12,199.
Tustin is the smallest city in Osceola County, with a population of 250.
There are 23 cities in Osceola County, Michigan.