20 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| South Bend | 1 | 103,435 | 103,335 | 0.02% | 2,469 | 42 | City |
| Penn | 2 | 68,490 | 68,596 | 0.01% | 1,093 | 63 | Township |
| Mishawaka | 3 | 50,708 | 51,042 | -0.13% | 2,813 | 18 | City |
| Clay | 4 | 34,446 | 34,198 | 0.27% | 1,740 | 20 | Township |
| Granger | 5 | 29,907 | 30,499 | -0.13% | 1,216 | 25 | CDP |
| Harris | 6 | 24,668 | 24,448 | 0.3% | 1,174 | 21 | Township |
| Centre | 7 | 14,542 | 14,397 | 0.35% | 752 | 19 | Township |
| German | 8 | 10,097 | 9,990 | 0.36% | 601 | 17 | Township |
| Notre Dame | 9 | 6,606 | 6,699 | 0.66% | 5,589 | 1 | CDP |
| Olive | 10 | 4,395 | 4,350 | 0.27% | 77 | 57 | Township |
| Union | 11 | 3,506 | 3,476 | 0.34% | 82 | 43 | Township |
| Greene | 12 | 2,968 | 2,947 | 0.3% | 86 | 34 | Township |
| Lincoln | 13 | 2,895 | 2,869 | 0.45% | 130 | 22 | Township |
| Osceola | 14 | 2,597 | 2,586 | 0.08% | 1,924 | 1 | Town |
| Walkerton | 15 | 2,089 | 2,094 | -0.05% | 1,099 | 2 | Town |
| New Carlisle | 16 | 1,921 | 1,893 | 0.31% | 947 | 2 | Town |
| North Liberty | 17 | 1,625 | 1,625 | 0% | 1,581 | 1 | Town |
| Lakeville | 18 | 877 | 874 | 0.11% | 1,401 | 1 | Town |
| Roseland | 19 | 851 | 851 | 0% | 2,257 | 0 | Town |
| Indian Village | 20 | 116 | 118 | 0% | 1,289 | 0 | Town |
South Bend is the largest city in St. Joseph County, with a population of 103,435.
Indian Village is the smallest city in St. Joseph County, with a population of 116.
There are 20 cities in St. Joseph County, Indiana.