Fracking, or hydraulic fracturing, relies on injecting water, sand and some chemicals deep beneath the earth's surface to break up rock and free up oil and gas trapped below.
Environmentalists say the chemicals used in the process can pollute underground water supplies and cause other damage.
Advocates say the Santa Cruz County ban is intended to pressure California Governor Jerry Brown into agreeing to put a halt to the practice in the state, a step he refused to take in the last legislative session.
Brown has said he supports fracking because he believes it is better for the state to produce its own crude oil than rely on imports.
"While Governor Brown refuses to protect our health and environment from fracking risks, local communities across the state are moving forward with measures to fight oil industry pollution," said Rose Braz of the Center for Biological Diversity in San Francisco.
An oil industry representative on Tuesday played down the significance of the Santa Cruz vote, calling it "symbolic."
"Activists are going around the state pursuing total bans on oil and gas development under the guise of wanting to ban fracking, but in places where people earn their livings responsibly producing our oil and gas resources, this strategy won't work," said Dave Quast, California director ofEnergy In Depth, an oil industry-backed group.
The action in Santa Cruz follows a vote earlier this month by city leaders in Beverly Hills to ban fracking, making it the first municipality in the state to prohibit the practice.
Los Angeles and Culver City are considering bans on fracking as well. Nationwide, there is a growing list of towns, cities and counties that have either banned or placed moratoriums on fracking. Dallas has an ordinance that effectively bans fracking within city limits. Dozens of towns in New York, Colorado and other states where wells are becoming increasingly common have also come out against the practice.
Al Jazeera and Reuters