Coconino County is a county located in the north central part of the U.S. state of Arizona. It is part of the Flagstaff, Arizona Metropolitan Statistical Area. The population was 116,320 at the 2000 census; the 2007 estimated population is 127,450.

The county seat is Flagstaff.It is the second largest county by land area in the 48 continguous United States, behind San Bernardino County, California, with its 18,661 square miles (48,300 km2) making it larger than each of the nine smallest states.

Coconino County contains Grand Canyon National Park, the Havasupai Nation, and parts of the Navajo Nation, Hualapai Nation, and Hopi Nation. It takes its name from Cosnino, a name applied to the Havasupai. Coconino County has a relatively large Native American population at nearly 30% of the county's total population, being mostly Navajo with smaller numbers of Havasupai, Hopi, and others.