27 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Rochester | 1 | 122,971 | 121,575 | 0.23% | 2,177 | 56.49 | City |
| Byron | 2 | 7,119 | 6,328 | 2.27% | 2,291 | 3.11 | City |
| Stewartville | 3 | 7,050 | 6,684 | 1.05% | 2,136 | 3.30 | City |
| Marion township | 4 | 4,272 | 4,031 | 1.42% | 147 | 29.10 | Township |
| Cascade township | 5 | 2,792 | 2,838 | -0.43% | 242 | 11.53 | Township |
| Oronoco township | 6 | 2,610 | 2,448 | 1.52% | 83 | 31.30 | Township |
| Rochester township | 7 | 2,241 | 2,078 | 1.36% | 125 | 17.91 | Township |
| Eyota | 8 | 2,033 | 1,998 | 0.35% | 1,204 | 1.69 | City |
| Oronoco | 9 | 1,761 | 1,810 | -0.56% | 601 | 2.93 | City |
| Haverhill township | 10 | 1,435 | 1,499 | -1.31% | 45 | 31.97 | Township |
| New Haven township | 11 | 1,266 | 1,259 | -0.24% | 38 | 33.70 | Township |
| Kalmar township | 12 | 1,175 | 1,122 | 1.29% | 36 | 32.50 | Township |
| Salem township | 13 | 1,041 | 1,090 | -1.14% | 29 | 35.77 | Township |
| High Forest township | 14 | 934 | 967 | -0.85% | 24 | 39.63 | Township |
| Dover | 15 | 774 | 784 | -0.26% | 771 | 1 | City |
| Pleasant Grove township | 16 | 709 | 750 | -1.39% | 20 | 35.76 | Township |
| Rock Dell township | 17 | 694 | 685 | 0.58% | 19 | 35.90 | Township |
| Orion township | 18 | 524 | 546 | -1.32% | 15 | 35.63 | Township |
| Viola township | 19 | 520 | 549 | -1.33% | 15 | 35.65 | Township |
| Eyota township | 20 | 516 | 489 | 1.18% | 15 | 34.08 | Township |
| Marion | 21 | 471 | 326 | 7.05% | 253 | 1.86 | CDP |
| Dover township | 22 | 389 | 383 | 0.52% | 11 | 34.86 | Township |
| Elmira township | 23 | 359 | 346 | 0.84% | 10 | 34.87 | Township |
| Quincy township | 24 | 348 | 328 | 1.46% | 10 | 35.76 | Township |
| Byron township | 25 | 209 | 209 | 0% | 6 | 36.04 | Township |
| Byron township | 26 | 160 | 150 | 0.63% | 4 | 35.71 | Township |
| Hammond | 27 | 131 | 131 | 0% | 819 | 0.16 | City |
Rochester is the largest city in Olmsted County, with a population of 122,971.
Hammond is the smallest city in Olmsted County.
There are 27 cities in Olmsted County, Minnesota.