33 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 |
| Tamalpais-Homestead Valley | 6 | 12,561 | 12,331 | 0.97% | 2,681 | 5 | CDP |
| Corte Madera | 7 | 9,956 | 10,206 | -0.5% | 3,151 | 3 | Town |
| Tiburon | 8 | 8,881 | 9,138 | -0.58% | 1,978 | 4 | Town |
| Kentfield | 9 | 7,641 | 7,423 | 1.02% | 2,524 | 3 | CDP |
| Fairfax | 10 | 7,446 | 7,593 | -0.4% | 3,342 | 2 | Town |
| Sausalito | 11 | 7,029 | 7,257 | -0.65% | 3,985 | 2 | City |
| Lucas Valley-Marinwood | 12 | 6,394 | 6,738 | 0.31% | 1,116 | 6 | CDP |
| Santa Venetia | 13 | 3,658 | 3,891 | -1.14% | 998 | 4 | CDP |
| Marin City | 14 | 3,607 | 3,040 | 1.78% | 6,717 | 1 | CDP |
| Sleepy Hollow | 15 | 2,877 | 2,366 | 1.16% | 970 | 3 | CDP |
| Ross | 16 | 2,288 | 2,331 | -0.39% | 1,469 | 2 | Town |
| Fairfax | 17 | 2,220 | 1,778 | 7.14% | 2,332 | 1 | CDP |
| Belvedere | 18 | 2,068 | 2,126 | -0.58% | 3,985 | 1 | City |
| Black Point-Green Point | 19 | 1,778 | 1,738 | 1.77% | 650 | 3 | CDP |
| Lagunitas-Forest Knolls | 20 | 1,729 | 1,874 | -0.35% | 407 | 4 | CDP |
| Inverness | 21 | 1,510 | 1,497 | 0.94% | 236 | 6 | CDP |
| Woodacre | 22 | 1,399 | 1,464 | 0.21% | 779 | 2 | CDP |
| Bolinas | 23 | 1,195 | 1,223 | -2.29% | 205 | 6 | CDP |
| Petaluma Center | 24 | 1,061 | 1,020 | 7.17% | 905 | 1 | CDP |
| Alto | 25 | 646 | 818 | -0.62% | 5,127 | 0 | CDP |
| Dillon Beach | 26 | 482 | 309 | 2.99% | 162 | 3 | CDP |
| Muir Beach | 27 | 431 | 360 | 1.89% | 874 | 0 | CDP |
| San Geronimo | 28 | 422 | 176 | -0.47% | 280 | 2 | CDP |
| Stinson Beach | 29 | 306 | 583 | -6.71% | 343 | 1 | CDP |
| Point Reyes Station | 30 | 267 | 210 | -12.75% | 74 | 4 | CDP |
| Tomales | 31 | 172 | 160 | -1.15% | 518 | 0 | CDP |
| Bloomfield | 32 | 160 | 243 | -6.98% | 20 | 8 | CDP |
| Nicasio | 33 | 104 | 123 | 7.22% | 80 | 1 | CDP |
San Rafael is the largest city in Marin County, with a population of 59,665.
Nicasio is the smallest city in Marin County, with a population of 104.
There are 33 cities in Marin County, California.