Khao Yai National Park is in the western part of the Sankamphaeng Mountain Range, at the southwestern boundary of the Khorat Plateau. The highest mountain in the area of the park is 1,351 m high Khao Rom.

This park lies largely in Nakhon Ratchasima Province (Khorat), but also includes parts of Saraburi, Prachinburi, and Nakhon Nayok Provinces.