Yarnell is a census-designated place (CDP) in Yavapai County, Arizona, USA. The population was 645 at the 2000 census. Yarnell's economy is based on ranching, mining and services to travelers and retirees. Peeples Valley, three miles north, is closely linked to Yarnell.
Gold was discovered in Yarnell about 1865 by Charles Genung (1839–1916), a well-known area pioneer. The community is named for Harrison Yarnell, a later prospector, who discovered the Yarnell mine in 1873. Old U.S. Route 89 (now State Route 89), which goes through Yarnell, was paved in 1933, and for many years was the main highway from Phoenix to Wickenburg, Prescott and northern Arizona.
Yarnell is located at 34°13′21″N 112°44′59″W / 34.2225°N 112.74972°W / 34.2225; -112.74972 (34.222569, -112.749608).