33 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| San Mateo | 1 | 98,441 | 105,656 | -1.44% | 8,113 | 12.13 | City |
| Daly City | 2 | 96,483 | 104,858 | -1.71% | 12,632 | 7.64 | City |
| Redwood City | 3 | 79,068 | 83,887 | -1.2% | 4,089 | 19.34 | City |
| South San Francisco | 4 | 61,270 | 65,902 | -1.49% | 6,657 | 9.20 | City |
| San Bruno | 5 | 39,714 | 43,746 | -1.99% | 7,235 | 5.49 | City |
| Pacifica | 6 | 35,034 | 38,514 | -1.95% | 2,784 | 12.58 | City |
| Foster City | 7 | 31,144 | 33,733 | -1.64% | 8,224 | 3.79 | City |
| Menlo Park | 8 | 30,356 | 33,690 | -2.15% | 3,039 | 9.99 | City |
| Burlingame | 9 | 28,998 | 31,278 | -1.55% | 6,601 | 4.39 | City |
| San Carlos | 10 | 27,678 | 30,638 | -2.09% | 5,114 | 5.41 | City |
| East Palo Alto | 11 | 27,061 | 29,948 | -2.09% | 10,705 | 2.53 | City |
| Belmont | 12 | 25,531 | 28,258 | -2.09% | 5,514 | 4.63 | City |
| Millbrae | 13 | 21,386 | 23,138 | -1.61% | 6,542 | 3.27 | City |
| North Fair Oaks | 14 | 13,476 | 14,992 | -0.59% | 11,268 | 1.20 | CDP |
| Half Moon Bay | 15 | 10,661 | 11,771 | -2.04% | 1,708 | 6.24 | City |
| Hillsborough | 16 | 10,563 | 11,363 | -1.49% | 1,713 | 6.17 | Town |
| Atherton | 17 | 6,591 | 7,171 | -1.73% | 1,314 | 5.02 | Town |
| El Granada | 18 | 5,697 | 6,069 | 0.26% | 1,160 | 4.91 | CDP |
| Woodside | 19 | 4,867 | 5,291 | -1.72% | 424 | 11.47 | Town |
| Broadmoor | 20 | 4,480 | 4,140 | 0.45% | 10,370 | 0.43 | CDP |
| Emerald Lake Hills | 21 | 4,462 | 4,893 | 0.27% | 3,775 | 1.18 | CDP |
| Brisbane | 22 | 4,401 | 4,840 | -1.96% | 1,474 | 2.98 | City |
| Portola Valley | 23 | 4,042 | 4,447 | -1.96% | 445 | 9.08 | Town |
| Highlands | 24 | 3,412 | 2,985 | 7.13% | 2,625 | 1.30 | CDP |
| West Menlo Park | 25 | 3,336 | 3,720 | -0.66% | 6,878 | 0.48 | CDP |
| Moss Beach | 26 | 3,180 | 3,436 | 0.16% | 1,422 | 2.24 | CDP |
| Montara | 27 | 2,584 | 2,833 | -0.84% | 666 | 3.88 | CDP |
| Baywood Park | 28 | 2,109 | 1,786 | 7.16% | 3,856 | 0.55 | CDP |
| La Honda | 29 | 1,546 | 1,229 | 2.79% | 363 | 4.26 | CDP |
| Ladera | 30 | 1,427 | 1,385 | 0% | 3,319 | 0.43 | CDP |
| Colma | 31 | 1,346 | 1,498 | -2.18% | 712 | 1.89 | Town |
| Pescadero | 32 | 276 | 418 | -8% | 69 | 4.03 | CDP |
| Loma Mar | 33 | 112 | 282 | 0% | 65 | 1.73 | CDP |
San Mateo is the largest city in San Mateo County, with a population of 98,441.
Loma Mar is the smallest city in San Mateo County.
There are 33 cities in San Mateo County, California.