Yavapai County is located near the center of the U.S. state of Arizona. As of 2007, its population was estimated to be 212,635, an increase of 45,118 people since the 2000 census count of 167,517. The county seat is Prescott.

Yavapai County was the one of four original Arizona Counties created by the 1st Arizona Territorial Legislature. The county territory was defined as being east of latitude 113° 20' and north of the Gila River. . Soon thereafter, the counties of Apache, Coconino, Maricopa, and Navajo were carved from the original Yavapai County.

Yavapai County's present boundaries were established in 1891. The county is named after the Yavapai people, who were the principal inhabitants at the time that this area was annexed by the United States.