18 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Manhattan | 1 | 53,364 | 54,158 | -0.3% | 2,659 | 20.07 | City |
| Manhattan township | 2 | 2,186 | 2,218 | -0.09% | 69 | 31.66 | Township |
| Ogden township | 3 | 1,998 | 2,069 | -0.6% | 161 | 12.38 | Township |
| Ogden | 4 | 1,601 | 1,668 | -0.81% | 957 | 1.67 | City |
| Riley | 5 | 919 | 943 | -0.54% | 1,809 | 0.51 | City |
| Grant township | 6 | 871 | 894 | -0.46% | 24 | 35.60 | Township |
| Wildcat township | 7 | 836 | 843 | -0.12% | 29 | 29.20 | Township |
| Bala township | 8 | 669 | 681 | -0.45% | 16 | 41.92 | Township |
| Sherman township | 9 | 571 | 579 | 0% | 19 | 29.40 | Township |
| Leonardville | 10 | 425 | 434 | -0.47% | 1,389 | 0.31 | City |
| Keats | 11 | 350 | 210 | 7.03% | 759 | 0.46 | CDP |
| Zeandale township | 12 | 329 | 339 | -0.6% | 6 | 59.58 | Township |
| Jackson township | 13 | 292 | 297 | 0% | 9 | 32.01 | Township |
| Swede Creek township | 14 | 166 | 166 | 0.61% | 3 | 48.65 | Township |
| Randolph | 15 | 153 | 160 | -0.65% | 556 | 0.28 | City |
| Fancy Creek township | 16 | 84 | 88 | -1.18% | 3 | 32.04 | Township |
| May Day township | 17 | 73 | 71 | 1.39% | 2 | 31.28 | Township |
| Center township | 18 | 70 | 74 | -1.41% | 2 | 31.59 | Township |
Manhattan is the largest city in Riley County, with a population of 53,364.
Center township is the smallest city in Riley County.
There are 18 cities in Riley County, Kansas.