33 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| San Mateo | 1 | 102,343 | 105,658 | -0.64% | 8,434 | 12 | City |
| Daly City | 2 | 100,536 | 104,945 | -0.87% | 13,163 | 8 | City |
| Redwood City | 3 | 82,758 | 83,875 | -0.27% | 4,280 | 19 | City |
| South San Francisco | 4 | 64,349 | 65,903 | -0.48% | 6,991 | 9 | City |
| San Bruno | 5 | 41,606 | 43,750 | -1.02% | 7,580 | 5 | City |
| Pacifica | 6 | 36,684 | 38,541 | -1% | 2,915 | 13 | City |
| Menlo Park | 7 | 32,877 | 33,689 | -0.49% | 3,291 | 10 | City |
| Foster City | 8 | 32,387 | 33,737 | -0.83% | 8,552 | 4 | City |
| Burlingame | 9 | 30,786 | 31,279 | -0.32% | 7,008 | 4 | City |
| East Palo Alto | 10 | 29,134 | 29,944 | -0.55% | 11,525 | 3 | City |
| San Carlos | 11 | 29,091 | 30,648 | -1.06% | 5,375 | 5 | City |
| Belmont | 12 | 26,848 | 28,265 | -1.05% | 5,799 | 5 | City |
| Millbrae | 13 | 23,366 | 23,138 | 0.19% | 7,148 | 3 | City |
| North Fair Oaks | 14 | 13,476 | 14,992 | -0.59% | 11,268 | 1 | CDP |
| Half Moon Bay | 15 | 11,213 | 11,767 | -0.98% | 1,796 | 6 | City |
| Hillsborough | 16 | 11,123 | 11,360 | -0.43% | 1,804 | 6 | Town |
| Atherton | 17 | 6,984 | 7,173 | -0.54% | 1,392 | 5 | Town |
| El Granada | 18 | 5,697 | 6,069 | 0.26% | 1,160 | 5 | CDP |
| Woodside | 19 | 5,081 | 5,290 | -0.82% | 443 | 11 | Town |
| Brisbane | 20 | 4,623 | 4,841 | -0.94% | 1,549 | 3 | City |
| Broadmoor | 21 | 4,480 | 4,140 | 0.45% | 10,370 | 0 | CDP |
| Emerald Lake Hills | 22 | 4,462 | 4,893 | 0.27% | 3,775 | 1 | CDP |
| Portola Valley | 23 | 4,241 | 4,446 | -0.96% | 467 | 9 | Town |
| Highlands | 24 | 3,412 | 2,985 | 7.13% | 2,625 | 1 | CDP |
| West Menlo Park | 25 | 3,336 | 3,720 | -0.66% | 6,878 | 0 | CDP |
| Moss Beach | 26 | 3,180 | 3,436 | 0.16% | 1,422 | 2 | CDP |
| Montara | 27 | 2,584 | 2,833 | -0.84% | 666 | 4 | CDP |
| Baywood Park | 28 | 2,109 | 1,786 | 7.16% | 3,856 | 1 | CDP |
| La Honda | 29 | 1,546 | 1,229 | 2.79% | 363 | 4 | CDP |
| Ladera | 30 | 1,427 | 1,385 | 0% | 3,319 | 0 | CDP |
| Colma | 31 | 1,410 | 1,497 | -1.26% | 746 | 2 | Town |
| Pescadero | 32 | 276 | 418 | -8% | 69 | 4 | CDP |
| Loma Mar | 33 | 112 | 282 | 0% | 65 | 2 | CDP |
San Mateo is the largest city in San Mateo County, with a population of 102,343.
Loma Mar is the smallest city in San Mateo County, with a population of 112.
There are 33 cities in San Mateo County, California.