| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Fairfield | 1 | 123,094 | 119,890 | 0.49% | 2,960 | 42 | City |
| Vallejo | 2 | 122,705 | 125,939 | -0.47% | 4,032 | 30 | City |
| Vacaville | 3 | 104,333 | 102,117 | 0.47% | 3,493 | 30 | City |
| Suisun City | 4 | 29,448 | 29,479 | -0.02% | 7,353 | 4 | City |
| Benicia | 5 | 26,254 | 27,109 | -0.56% | 2,049 | 13 | City |
| Dixon | 6 | 21,381 | 19,462 | 1.25% | 3,011 | 7 | City |
| Rio Vista | 7 | 10,602 | 10,012 | 0.75% | 1,606 | 7 | City |
Fairfield is the largest city in Solano County, with a population of 123,094.
Rio Vista is the smallest city in Solano County, with a population of 10,602.
There are 7 cities in Solano County, California.