26 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Ionia | 1 | 11,708 | 13,378 | -2.32% | 2,164 | 5 | City |
| Boston | 2 | 6,118 | 6,034 | 0.28% | 174 | 35 | Township |
| Belding | 3 | 5,978 | 5,945 | 0.1% | 1,265 | 5 | City |
| Ionia | 4 | 4,118 | 3,990 | 0.49% | 123 | 33 | Township |
| Portland | 5 | 3,971 | 3,895 | 0.33% | 123 | 32 | Township |
| Odessa | 6 | 3,947 | 3,915 | 0.13% | 111 | 36 | Township |
| Portland | 7 | 3,750 | 3,809 | -0.27% | 1,426 | 3 | City |
| Lyons | 8 | 3,564 | 3,518 | 0.22% | 99 | 36 | Township |
| Easton | 9 | 3,128 | 3,057 | 0.39% | 110 | 28 | Township |
| Danby | 10 | 2,999 | 2,956 | 0.33% | 85 | 35 | Township |
| Orleans | 11 | 2,747 | 2,672 | 0.44% | 78 | 35 | Township |
| Campbell | 12 | 2,423 | 2,399 | 0.17% | 68 | 36 | Township |
| Otisco | 13 | 2,300 | 2,276 | 0.17% | 74 | 31 | Township |
| Berlin | 14 | 2,161 | 2,139 | 0.23% | 52 | 41 | Township |
| Lake Odessa | 15 | 2,072 | 2,051 | 0.19% | 2,328 | 1 | Village |
| Ronald | 16 | 1,904 | 1,855 | 0.42% | 53 | 36 | Township |
| Keene | 17 | 1,744 | 1,728 | 0.11% | 49 | 36 | Township |
| Saranac | 18 | 1,381 | 1,375 | 0.07% | 1,201 | 1 | Village |
| North Plains | 19 | 1,202 | 1,187 | 0.25% | 34 | 36 | Township |
| Sebewa | 20 | 1,151 | 1,131 | 0.35% | 32 | 36 | Township |
| Orange | 21 | 1,031 | 1,007 | 0.29% | 29 | 36 | Township |
| Lyons | 22 | 779 | 772 | 0.13% | 640 | 1 | Village |
| Muir | 23 | 646 | 642 | 0.16% | 907 | 1 | Village |
| Pewamo | 24 | 518 | 515 | 0.19% | 518 | 1 | Village |
| Clarksville | 25 | 402 | 399 | 0.25% | 798 | 1 | Village |
| Hubbardston | 26 | 345 | 341 | 0.29% | 237 | 1 | Village |
Ionia is the largest city in Ionia County, with a population of 11,708.
Hubbardston is the smallest city in Ionia County, with a population of 345.
There are 26 cities in Ionia County, Michigan.