9 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Santa Rosa | 1 | 177,412 | 177,972 | -0.06% | 4,171 | 43 | City |
| Petaluma | 2 | 59,304 | 59,749 | -0.15% | 4,114 | 14 | City |
| Rohnert Park | 3 | 45,001 | 44,465 | 0.24% | 6,176 | 7 | City |
| Windsor | 4 | 25,721 | 26,344 | -0.48% | 3,459 | 7 | Town |
| Healdsburg | 5 | 11,200 | 11,353 | -0.28% | 2,534 | 4 | City |
| Sonoma | 6 | 10,576 | 10,726 | -0.28% | 3,854 | 3 | City |
| Cloverdale | 7 | 8,725 | 9,018 | -0.67% | 2,594 | 3 | City |
| Cotati | 8 | 7,355 | 7,592 | -0.65% | 3,925 | 2 | City |
| Sebastopol | 9 | 7,355 | 7,519 | -0.45% | 3,908 | 2 | City |
Santa Rosa is the largest city in Sonoma County, with a population of 177,412.
Sebastopol is the smallest city in Sonoma County, with a population of 7,355.
There are 9 cities in Sonoma County, California.