11 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Kennewick | 1 | 87,410 | 83,940 | 0.79% | 3,067 | 29 | City |
| Kennewick | 2 | 87,410 | 84,000 | 0.79% | 3,067 | 29 | City |
| Richland | 3 | 65,242 | 60,575 | 1.35% | 1,636 | 40 | City |
| Richland | 4 | 65,242 | 60,892 | 1.35% | 1,636 | 40 | City |
| West Richland | 5 | 19,428 | 16,300 | 3.23% | 878 | 22 | City |
| West Richland | 6 | 19,428 | 16,387 | 3.23% | 878 | 22 | City |
| Prosser | 7 | 6,638 | 6,137 | 1.5% | 1,284 | 5 | City |
| Prosser | 8 | 6,638 | 6,146 | 1.5% | 1,284 | 5 | City |
| Finley | 9 | 5,807 | 5,858 | -0.24% | 502 | 12 | CDP |
| Benton City | 10 | 3,973 | 3,490 | 2.5% | 1,596 | 2 | City |
| Benton City | 11 | 3,973 | 3,486 | 2.5% | 1,596 | 2 | City |
Kennewick is the largest city in Benton County, with a population of 87,410.
Benton City is the smallest city in Benton County, with a population of 3,973.
There are 11 cities in Benton County, Washington.