It is fenced on three sides, whereas the open southern boundary allows migrating wildlife to move between the park and the adjacent Kitengela plains.

Nairobi National Park is negatively affected by increasing human and livestock populations, changing land use and poaching of wildlife.

[2] Despite its proximity to the city and its relative small size, it boasts a large and varied wildlife population,[3] and is one of Kenya's most successful rhinoceros sanctuaries.

Animals were gradually confined to the expansive plains to the west and south of Nairobi, and the colonial government set this area aside as a game reserve.

Settlers from Nairobi including Isak Dinesen, author of Out of Africa, rode horses among gazelles, impala, and zebras in this reserve.

Returning to Kenya after a nine-year absence in 1932,[6] he was alarmed to see that the amount of game animals on the Athi plains had dwindled.

Hunting was not permitted in the reserve, but nearly every other activity, including cattle grazing, dumping, and even bombing by the Royal Air Force was allowed.

[5] In 1989, Kenyan President Daniel arap Moi burned twelve tons of ivory on a site within the park.

This boundary is not fenced and is open to the Kitengela Conservation Area (located immediately south of the park) and the Athi-Kapiti plains.

The western uplands of the park have highland dry forest with stands of Olea africana, Croton dichogamus, Brachylaena hutchinsii, and Calodendrum.

[3] Species found in the park include lion, leopard, African buffalo, black rhinoceros, giraffe, hippopotamus, spotted hyena, blue wildebeest, plains zebra, cheetah, Thomson's gazelle, Grant's gazelle, common eland, impala, hartebeest, waterbuck, common warthog, olive baboon, black-backed jackal, common ostrich, and Nile crocodile.

[11][13] Herbivores, including wildebeest and zebra, use the Kitengela conservation area and migration corridor to the south of the park to reach the Athi-Kapiti plains.

Small dams built along the Mbagathi River give the park more water resources than these outside areas.

[14] Nairobi National Park is sometimes called Kifaru Ark, which means "Rhinoceros Sanctuary".

[4] Mervyn Cowie oversaw the development of several of Kenya's national parks and designed them with human visitors in mind.

[16] Treaties with the Maasai in 1904 and 1911 forced them to give up all of their northern grazing lands on the Laikipia escarpment near Mount Kenya.

Migrating animals can reach their southern pastures by travelling through the part of the Athi plains called the Kitengela.

[5] The park's migratory species are also threatened by changing settlement patterns, fencing, and their closeness to Nairobi and other industrial towns.

Visitor attractions include the park's diverse bird species, cheetah, hyena, leopard, and lion.

Other attractions are the wildebeest and zebra migrations in July and August, the Ivory Burning Site Monument, and the Nairobi Safari Walk and animal orphanage.