Hillsborough is an incorporated town in San Mateo County, California, United States, in the San Francisco Bay Area. It is located 17 miles (27 km) south of San Francisco on the San Francisco Peninsula, bordered by Burlingame to the north, San Mateo to the east, Highlands-Baywood Park to the south, and Interstate 280 to the west. The population was 11,387 at the 2020 census.

The San Francisco Peninsula is a peninsula in the San Francisco Bay Area that separates San Francisco Bay from the Pacific Ocean. On its northern tip is the City and County of San Francisco. Its southern base is Los Altos, Mountain View, in Santa Clara County, south of Palo Alto and north of Sunnyvale and Los Altos. Most of the Peninsula is occupied by San Mateo County, between San Francisco and Santa Clara counties, and including the cities and towns of Atherton, Belmont, Brisbane, Burlingame, Colma, Daly City, East Palo Alto, El Granada, Foster City, Hillsborough, Half Moon Bay, La Honda, Loma Mar, Los Altos, Menlo Park, Millbrae, Mountain View, Pacifica, Palo Alto, Pescadero, Portola Valley, Redwood City, San Bruno, San Carlos, San Mateo, South San Francisco, and Woodside.