Inyo County is located in east-central California in the southwestern United States, on the east side of the Sierra Nevada Mountains and south of Yosemite National Park. As of 2000 the county had a population of 17,945. The county seat is Independence.

Mount Whitney, the highest peak in the lower 48 states, is located in Inyo County. Badwater in Death Valley National Park, the lowest point in the Western Hemisphere, is also located in the county. The two points are not visible from each other, but both can be observed from the Panamint Range on the west side of Death Valley.

According to the U.S. Census Bureau, the county has a total area of 10,227 square miles, of which 10,203 sq mi is land and the remaining 24 sq mi is water. Relatively, it is a very large county. It is the second largest in California and the tenth largest in the nation (excluding boroughs and census areas in Alaska).

Inyo County was formed in 1866 from parts of Mono and Tulare Counties.

The county derived its name from the Native American name for the mountains in its area. The meaning of the word inyo is "dwelling place of the great spirit."