Fresno County is a county located in the Central Valley of the U.S. state of California, south of Stockton and north of Bakersfield. As of 2008, it is the tenth most populous county in California with an estimated population of 931,098 , and the sixth largest in size with an area of 6,017.4 square miles (15,585 km2). The county seat is Fresno.

In 2009 Fresno was the fifth largest city in California. The area now known as Fresno County, once a semiarid steppe, was discovered by Spaniards during a search for suitable mission sites. In 1846, this area became the property of the United States as a result of the Mexican War. Fresno County was formed in 1856 from parts of Mariposa, Merced and Tulare counties. The county is named after Fresno Creek. Fresno in Spanish signifies "ash tree" and it was due to the abundance of mountain ash or ash trees in the county that it received its name.