25 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Sturgis | 1 | 10,932 | 11,132 | -0.36% | 1,609 | 6.80 | City |
| Three Rivers | 2 | 7,900 | 7,969 | -0.18% | 1,413 | 5.59 | City |
| Constantine | 3 | 4,037 | 4,046 | 0.05% | 117 | 34.49 | Township |
| Lockport | 4 | 3,810 | 3,742 | 0.58% | 134 | 28.47 | Township |
| White Pigeon | 5 | 3,804 | 3,761 | 0.32% | 151 | 25.14 | Township |
| Nottawa | 6 | 3,762 | 3,688 | 0.48% | 106 | 35.60 | Township |
| Sherman | 7 | 3,450 | 3,443 | -0.12% | 105 | 32.97 | Township |
| Colon | 8 | 3,358 | 3,329 | 0.39% | 98 | 34.37 | Township |
| Fabius | 9 | 3,318 | 3,311 | 0.03% | 104 | 31.98 | Township |
| Burr Oak | 10 | 2,667 | 2,632 | 0.49% | 76 | 35.25 | Township |
| Mendon | 11 | 2,606 | 2,577 | 0.39% | 75 | 34.95 | Township |
| Park | 12 | 2,382 | 2,395 | 0% | 68 | 34.95 | Township |
| Nottawa | 13 | 2,193 | 2,181 | -0.18% | 62 | 35.31 | Township |
| Sturgis | 14 | 2,020 | 2,040 | -0.15% | 116 | 17.44 | Township |
| Constantine | 15 | 1,988 | 1,993 | -0.05% | 1,215 | 1.64 | Village |
| White Pigeon | 16 | 1,721 | 1,731 | -0.12% | 1,221 | 1.41 | Village |
| Flowerfield | 17 | 1,615 | 1,592 | 0.19% | 46 | 35.46 | Township |
| Fawn River | 18 | 1,525 | 1,535 | -0.07% | 80 | 19.12 | Township |
| Mottville | 19 | 1,458 | 1,445 | 0.21% | 75 | 19.32 | Township |
| Centreville | 20 | 1,319 | 1,323 | -0.08% | 891 | 1.48 | Village |
| Colon | 21 | 1,188 | 1,212 | -0.42% | 865 | 1.37 | Village |
| Leonidas | 22 | 1,160 | 1,157 | 0.09% | 33 | 35.51 | Township |
| Florence | 23 | 1,150 | 1,147 | 0.17% | 35 | 33.24 | Township |
| Mendon | 24 | 858 | 882 | -0.58% | 877 | 0.98 | Village |
| Burr Oak | 25 | 750 | 774 | -0.66% | 746 | 1.01 | Village |
Sturgis is the largest city in St. Joseph County, with a population of 10,932.
Burr Oak is the smallest city in St. Joseph County, with a population of 750.
There are 25 cities in St. Joseph County, Michigan.