25 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Watertown | 1 | 23,694 | 22,683 | 0.86% | 1,285 | 18 | City |
| Pelican | 2 | 771 | 742 | 0.92% | 26 | 30 | Township |
| Lake | 3 | 676 | 657 | 1.05% | 33 | 21 | Township |
| Sheridan | 4 | 494 | 481 | 0.82% | 15 | 32 | Township |
| Elmira | 5 | 445 | 439 | 0.45% | 15 | 29 | Township |
| Florence | 6 | 333 | 332 | 0% | 481 | 1 | Town |
| Kranzburg | 7 | 325 | 313 | 0.93% | 5 | 61 | Township |
| Kampeska | 8 | 317 | 311 | 0.32% | 9 | 35 | Township |
| Fuller | 9 | 309 | 297 | 1.31% | 6 | 54 | Township |
| Rauville | 10 | 290 | 284 | 0.35% | 6 | 50 | Township |
| Henry | 11 | 268 | 255 | 0.75% | 185 | 1 | Town |
| Dexter | 12 | 212 | 207 | 0.47% | 4 | 60 | Township |
| Waverly | 13 | 201 | 193 | 1.52% | 4 | 45 | Township |
| South Shore | 14 | 190 | 189 | 0% | 136 | 1 | Town |
| Kranzburg | 15 | 166 | 163 | 0% | 217 | 1 | Town |
| Germantown | 16 | 166 | 163 | 0% | 4 | 47 | Township |
| Florence | 17 | 166 | 149 | 1.84% | 5 | 34 | Township |
| Richland | 18 | 154 | 148 | 1.99% | 5 | 34 | Township |
| Henry | 19 | 120 | 122 | -0.83% | 3 | 36 | Township |
| Wallace | 20 | 94 | 93 | 0% | 707 | 0 | Town |
| Graceland | 21 | 94 | 91 | 1.08% | 3 | 33 | Township |
| Henry | 22 | 94 | 93 | 0% | 3 | 34 | Township |
| Phipps | 23 | 64 | 62 | 0% | 2 | 33 | Township |
| Florence | 24 | 28 | 30 | -3.45% | 1 | 36 | Township |
| Waverly | 25 | 26 | 51 | 8.33% | 26 | 1 | CDP |
Watertown is the largest city in Codington County, with a population of 23,694.
Waverly is the smallest city in Codington County, with a population of 26.
There are 25 cities in Codington County, South Dakota.