The park covers 2,512 km², mostly of lowland plains at a height of 330 m and 508 m above sea level. The southern part is drained by the Owu, Owe and Ogun Rivers, while the northern sector is drained by the Tessi River. Outcrops of granite are typical of the north eastern zone of the park, including at Oyo-lle, with caves and rock shelters in the extreme north. The central part of the park has scattered hills, ridges and rock outcrops that are suitable for mountaineering. The Ikere Gorge Dam on the Ogun river provides water recreation facilities for tourists.

Wildlife that can be found includes  populations of African buffalo, kob, bushbuck, roan antelope, western hartebeest, patas monkey, and waterbuck. The Old Oyo National Park was previously habitat for the endangered West African wild dog; however, the species has been extirpated from the park due to hunting pressure and the expanding human population in the region.