Campbell is a city in Santa Clara County, California, in the San Francisco Bay Area. As of the 2020 U.S. Census, Campbell's population is 43,9…Campbell is a city in Santa Clara County, California, in the San Francisco Bay Area. As of the 2020 U.S. Census, Campbell's population is 43,959. Campbell is home to the Pruneyard Shopping Center, a sprawling open-air retail complex which was involved in a famous U.S. Supreme Court case that established the extent of the right to free speech in California.