26 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Ionia | 1 | 11,503 | 13,368 | -3.14% | 2,126 | 5.41 | City |
| Boston township | 2 | 6,109 | 6,031 | 0.2% | 174 | 35.08 | Township |
| Belding | 3 | 5,989 | 5,946 | 0.15% | 1,268 | 4.72 | City |
| Ionia township | 4 | 4,101 | 3,987 | 0.49% | 122 | 33.48 | Township |
| Portland township | 5 | 3,986 | 3,887 | 0.45% | 124 | 32.18 | Township |
| Odessa township | 6 | 3,952 | 3,914 | 0.1% | 111 | 35.58 | Township |
| Portland | 7 | 3,784 | 3,816 | -0.16% | 1,439 | 2.63 | City |
| Lyons township | 8 | 3,570 | 3,517 | 0.25% | 99 | 35.92 | Township |
| Easton township | 9 | 3,114 | 3,053 | 0.32% | 109 | 28.44 | Township |
| Danby township | 10 | 2,988 | 2,956 | 0.17% | 85 | 35.13 | Township |
| Orleans township | 11 | 2,737 | 2,672 | 0.4% | 78 | 35.17 | Township |
| Campbell township | 12 | 2,422 | 2,402 | 0.08% | 68 | 35.73 | Township |
| Otisco township | 13 | 2,307 | 2,276 | 0.22% | 74 | 30.97 | Township |
| Berlin township | 14 | 2,159 | 2,138 | 0.14% | 52 | 41.43 | Township |
| Lake Odessa | 15 | 2,074 | 2,051 | 0.24% | 2,330 | 0.89 | Village |
| Ronald township | 16 | 1,914 | 1,857 | 0.58% | 53 | 36.19 | Township |
| Keene township | 17 | 1,752 | 1,727 | 0.23% | 49 | 35.58 | Township |
| Saranac | 18 | 1,386 | 1,373 | 0.22% | 1,205 | 1.15 | Village |
| North Plains township | 19 | 1,201 | 1,184 | 0.17% | 34 | 35.75 | Township |
| Sebewa township | 20 | 1,146 | 1,130 | 0.26% | 32 | 35.94 | Township |
| Orange township | 21 | 1,030 | 1,009 | 0.29% | 29 | 35.99 | Township |
| Lyons | 22 | 796 | 773 | 0.63% | 654 | 1.22 | Village |
| Muir | 23 | 648 | 642 | 0.15% | 910 | 0.71 | Village |
| Pewamo | 24 | 518 | 517 | 0% | 518 | 1 | Village |
| Clarksville | 25 | 399 | 398 | 0% | 792 | 0.50 | Village |
| Hubbardston | 26 | 345 | 339 | 0.29% | 237 | 1.45 | Village |
Ionia is the largest city in Ionia County, with a population of 11,503.
Hubbardston is the smallest city in Ionia County.
There are 26 cities in Ionia County, Michigan.