7 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Fairfield | 1 | 123,335 | 119,890 | 0.56% | 2,966 | 42 | City |
| Vallejo | 2 | 122,861 | 125,930 | -0.5% | 4,037 | 30 | City |
| Vacaville | 3 | 104,455 | 102,147 | 0.44% | 3,497 | 30 | City |
| Suisun City | 4 | 29,648 | 29,478 | 0.11% | 7,403 | 4 | City |
| Benicia | 5 | 26,319 | 27,107 | -0.6% | 2,054 | 13 | City |
| Dixon | 6 | 20,532 | 19,352 | 1.16% | 2,892 | 7 | City |
| Rio Vista | 7 | 10,308 | 10,008 | 0.59% | 1,562 | 7 | City |
Fairfield is the largest city in Solano County, with a population of 123,335.
Rio Vista is the smallest city in Solano County, with a population of 10,308.
There are 7 cities in Solano County, California.