Karura Forest has an area of 1 063.0 ha, making it largest of three main gazetted forests in Nairobi. The others are Ngong Forest and Oloolua Forest. The centrally located Nairobi Arboretum is much smaller.

Karura Forest is located nort of central Nairobi and is bordered by the suburbs of Muthaiga, Gigiri, Runda, Ridgeways, Mathare North, Peponi and New Muthaiga. The western part of the forest is also known as Sigiria Forest.

The area north of central Nairobi forms a drainage basin and was once heavily forested, but exists today only as patches like Karura Forest and City Park. The forest is cut by Thigirie, Getathuru, Rui Ruaka and Karura Rivers, all tributaries of Nairobi River.

Features in the forest include a waterfall, bamboo forest, marshland, Mau Mau caves and an old church.