11 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| San Rafael | 1 | 59,665 | 61,143 | -0.49% | 3,597 | 17 | City |
| Novato | 2 | 52,102 | 53,146 | -0.4% | 1,904 | 27 | City |
| Mill Valley | 3 | 13,829 | 14,203 | -0.54% | 2,892 | 5 | City |
| Larkspur | 4 | 12,750 | 13,035 | -0.45% | 4,251 | 3 | City |
| San Anselmo | 5 | 12,602 | 12,815 | -0.34% | 4,711 | 3 | Town |
| Corte Madera | 6 | 9,956 | 10,206 | -0.5% | 3,151 | 3 | Town |
| Tiburon | 7 | 8,881 | 9,138 | -0.58% | 1,978 | 4 | Town |
| Fairfax | 8 | 7,446 | 7,593 | -0.4% | 3,342 | 2 | Town |
| Sausalito | 9 | 7,029 | 7,257 | -0.65% | 3,985 | 2 | City |
| Ross | 10 | 2,288 | 2,331 | -0.39% | 1,469 | 2 | Town |
| Belvedere | 11 | 2,068 | 2,126 | -0.58% | 3,985 | 1 | City |
San Rafael is the largest city in Marin County, with a population of 59,665.
Belvedere is the smallest city in Marin County, with a population of 2,068.
There are 11 cities in Marin County, California.