25 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Sturgis | 1 | 10,974 | 11,141 | -0.25% | 1,615 | 7 | City |
| Three Rivers | 2 | 7,955 | 7,964 | -0.01% | 1,423 | 6 | City |
| Constantine | 3 | 4,069 | 4,046 | 0.1% | 118 | 34 | Township |
| Lockport | 4 | 3,906 | 3,740 | 1.14% | 137 | 28 | Township |
| White Pigeon | 5 | 3,837 | 3,764 | 0.42% | 153 | 25 | Township |
| Nottawa | 6 | 3,787 | 3,685 | 0.4% | 106 | 36 | Township |
| Sherman | 7 | 3,501 | 3,444 | 0.34% | 106 | 33 | Township |
| Colon | 8 | 3,380 | 3,334 | 0.3% | 98 | 34 | Township |
| Fabius | 9 | 3,330 | 3,313 | 0.03% | 104 | 32 | Township |
| Burr Oak | 10 | 2,673 | 2,633 | 0.3% | 76 | 35 | Township |
| Mendon | 11 | 2,584 | 2,574 | -0.08% | 74 | 35 | Township |
| Park | 12 | 2,400 | 2,396 | 0.13% | 69 | 35 | Township |
| Nottawa | 13 | 2,286 | 2,180 | 1.15% | 65 | 35 | Township |
| Sturgis | 14 | 2,012 | 2,040 | -0.3% | 115 | 17 | Township |
| Constantine | 15 | 2,004 | 1,991 | 0.1% | 1,225 | 2 | Village |
| White Pigeon | 16 | 1,730 | 1,732 | 0% | 1,228 | 1 | Village |
| Flowerfield | 17 | 1,626 | 1,593 | 0.25% | 46 | 35 | Township |
| Fawn River | 18 | 1,546 | 1,526 | 0.45% | 81 | 19 | Township |
| Mottville | 19 | 1,465 | 1,447 | 0.14% | 76 | 19 | Township |
| Centreville | 20 | 1,324 | 1,318 | 0.08% | 894 | 1 | Village |
| Colon | 21 | 1,188 | 1,212 | -0.34% | 865 | 1 | Village |
| Leonidas | 22 | 1,164 | 1,155 | 0.17% | 33 | 36 | Township |
| Florence | 23 | 1,139 | 1,147 | -0.18% | 34 | 33 | Township |
| Mendon | 24 | 856 | 882 | -0.47% | 875 | 1 | Village |
| Burr Oak | 25 | 751 | 774 | -0.53% | 747 | 1 | Village |
Sturgis is the largest city in St. Joseph County, with a population of 10,974.
Burr Oak is the smallest city in St. Joseph County, with a population of 751.
There are 25 cities in St. Joseph County, Michigan.