Navajo County is located in the northern part of the U.S. state of Arizona. As of 2000 its population was 97,470. The county seat is Holbrook. Navajo County contains parts of the Hopi Indian reservation, the Navajo Indian Reservation and Fort Apache Indian Reservation. Navajo County was split from Apache County on March 21, 1895.

The first county sheriff was legendary gunman Commodore Perry Owens, who had previously served as the sheriff of Apache County. It was the location for many of the events that played out during the Pleasant Valley War.