25 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Watertown | 1 | 23,597 | 22,679 | 0.79% | 1,280 | 18.44 | City |
| Pelican township | 2 | 761 | 742 | 0.53% | 26 | 29.74 | Township |
| Lake township | 3 | 671 | 662 | 0.3% | 33 | 20.65 | Township |
| Sheridan township | 4 | 488 | 479 | 0.41% | 15 | 31.90 | Township |
| Elmira township | 5 | 446 | 440 | 0.45% | 15 | 29.50 | Township |
| Florence | 6 | 334 | 333 | 0% | 482 | 0.69 | Town |
| Kranzburg township | 7 | 320 | 313 | 0.63% | 5 | 60.55 | Township |
| Kampeska township | 8 | 319 | 311 | 0.63% | 9 | 35.02 | Township |
| Fuller township | 9 | 304 | 296 | 0.66% | 6 | 54.14 | Township |
| Rauville township | 10 | 290 | 282 | 0.69% | 6 | 50.31 | Township |
| Henry | 11 | 269 | 253 | 1.13% | 185 | 1.45 | Town |
| Dexter township | 12 | 214 | 207 | 0.94% | 4 | 59.68 | Township |
| Waverly township | 13 | 193 | 191 | 0% | 4 | 45.39 | Township |
| South Shore | 14 | 188 | 190 | 0% | 135 | 1.40 | Town |
| Germantown township | 15 | 171 | 164 | 1.18% | 4 | 46.97 | Township |
| Florence township | 16 | 169 | 150 | 2.42% | 5 | 33.81 | Township |
| Kranzburg | 17 | 167 | 162 | 0.6% | 219 | 0.76 | Town |
| Richland township | 18 | 157 | 150 | 1.29% | 5 | 33.58 | Township |
| Henry township | 19 | 122 | 121 | 0% | 3 | 36.08 | Township |
| Wallace | 20 | 94 | 93 | 0% | 707 | 0.13 | Town |
| Henry township | 21 | 94 | 93 | 0% | 3 | 34.30 | Township |
| Graceland township | 22 | 91 | 90 | 0% | 3 | 33.08 | Township |
| Phipps township | 23 | 67 | 62 | 3.08% | 2 | 33.33 | Township |
| Florence township | 24 | 28 | 28 | 0% | 1 | 35.92 | Township |
| Waverly | 25 | 26 | 51 | 8.33% | 26 | 1.02 | CDP |
Watertown is the largest city in Codington County, with a population of 23,597.
Waverly is the smallest city in Codington County.
There are 25 cities in Codington County, South Dakota.