15 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Corvallis | 1 | 62,905 | 59,918 | 1.47% | 4,330 | 15 | City |
| Corvallis | 2 | 62,905 | 58,345 | 1.47% | 4,330 | 15 | City |
| Philomath | 3 | 5,908 | 5,352 | 1.95% | 2,862 | 2 | City |
| Philomath | 4 | 5,908 | 5,342 | 1.95% | 2,862 | 2 | City |
| Millersburg | 5 | 3,650 | 3,050 | 3.08% | 880 | 4 | City |
| Millersburg | 6 | 3,650 | 3,104 | 3.08% | 880 | 4 | City |
| Adair Village | 7 | 1,038 | 987 | 0.97% | 2,338 | 0 | City |
| Adair Village | 8 | 1,038 | 986 | 0.97% | 2,338 | 0 | City |
| Monroe | 9 | 685 | 645 | 1.18% | 1,330 | 1 | City |
| Monroe | 10 | 685 | 645 | 1.18% | 1,330 | 1 | City |
| Alpine | 11 | 262 | 215 | 2.34% | 305 | 1 | CDP |
| Summit | 12 | 221 | 267 | 7.28% | 693 | 0 | CDP |
| Kings Valley | 13 | 184 | 194 | 6.98% | 253 | 1 | CDP |
| Alsea | 14 | 133 | 220 | -1.48% | 853 | 0 | CDP |
| Bellfountain | 15 | 54 | 8 | 8% | 40 | 1 | CDP |
Corvallis is the largest city in Benton County, with a population of 62,905.
Bellfountain is the smallest city in Benton County, with a population of 54.
There are 15 cities in Benton County, Oregon.