Note: As defined by the US Census Bureau, a city's official boundaries often extend miles beyond the city itself and may even cross county lines. As such, several thousand US cities officially exist in two or more counties (and therefore appear on multiple counties' lists of cities.)
City | Rank | 2024 Pop. | 2020 Pop. | Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Ionia | 1 | 11,876 | 13,368 | -3.04% | 2,195 | 5.4 | City |
| Boston township | 2 | 6,097 | 6,031 | 0.2% | 174 | 35.1 | Township |
| Belding | 3 | 5,980 | 5,946 | 0.13% | 1,266 | 4.7 | City |
| Ionia township | 4 | 4,081 | 3,987 | 0.49% | 122 | 33.5 | Township |
| Portland township | 5 | 3,968 | 3,887 | 0.46% | 123 | 32.2 | Township |
| Odessa township | 6 | 3,948 | 3,914 | 0.1% | 111 | 35.6 | Township |
| Portland | 7 | 3,790 | 3,816 | -0.18% | 1,442 | 2.6 | City |
| Lyons township | 8 | 3,561 | 3,517 | 0.25% | 99 | 35.9 | Township |
| Easton township | 9 | 3,104 | 3,053 | 0.32% | 109 | 28.4 | Township |
| Danby township | 10 | 2,983 | 2,956 | 0.17% | 85 | 35.1 | Township |
| Orleans township | 11 | 2,726 | 2,672 | 0.4% | 78 | 35.2 | Township |
| Campbell township | 12 | 2,420 | 2,402 | 0.08% | 68 | 35.7 | Township |
| Otisco township | 13 | 2,302 | 2,276 | 0.22% | 74 | 31.0 | Township |
| Berlin township | 14 | 2,156 | 2,138 | 0.14% | 52 | 41.4 | Township |
| Lake Odessa | 15 | 2,069 | 2,051 | 0.19% | 2,325 | 0.9 | Village |
| Ronald township | 16 | 1,903 | 1,857 | 0.58% | 53 | 36.2 | Township |
| Keene township | 17 | 1,748 | 1,727 | 0.23% | 49 | 35.6 | Township |
| Saranac | 18 | 1,383 | 1,373 | 0.14% | 1,203 | 1.1 | Village |
| North Plains township | 19 | 1,199 | 1,184 | 0.17% | 34 | 35.8 | Township |
| Sebewa township | 20 | 1,143 | 1,130 | 0.26% | 32 | 35.9 | Township |
| Orange township | 21 | 1,027 | 1,009 | 0.29% | 29 | 36.0 | Township |
| Lyons | 22 | 791 | 773 | 0.51% | 650 | 1.2 | Village |
| Muir | 23 | 647 | 642 | 0.15% | 909 | 0.7 | Village |
| Pewamo | 24 | 518 | 517 | 0% | 518 | 1.0 | Village |
| Clarksville | 25 | 399 | 398 | 0% | 792 | 0.5 | Village |
| Hubbardston | 26 | 344 | 339 | 0.29% | 237 | 1.5 | Village |
Note: City markers shown outside the county boundary mean that a part of the city extends into this county, but is primarily located in an adjacent county.
Ionia is the largest city in Ionia County.
Hubbardston is the smallest city in Ionia County.
There are 26 cities in Ionia County, Michigan.