The species is the most wide-ranging of all baboons,[3] being native to 25 countries throughout Africa, extending from Mali eastward to Ethiopia[4] and Tanzania.

[5] This coloration is shared by both sexes, although males have a mane of longer hair that tapers down to ordinary length along the back.

[12] The species inhabits a strip of 25 equatorial African countries, very nearly ranging from the east to west coasts of the continent.

[13] The grasslands, especially those near open woodland, do make up a large part of its habitat, but the baboon also inhabits rainforests and deserts.

[3] Uganda and the Democratic Republic of the Congo, for instance, both support olive baboon populations in dense tropical forests.

[16] Occasionally, groups may split up when they become so large that competition for resources is problematic, but even then, members of matrilines tend to stick together.

[16] Males occasionally "baby-sit" for their female friends, so she can feed and forage freely without the burden of having to carry or watch the infant.

Another advantage of these friendships is it enables females to gain protection from the unwanted advances of males aiming to mate with them.

This also explains the reason male olive baboons use infants as shields in aggressive encounters.

[21] The swelling makes it difficult to move and increases the female's chance of microbial or parasitic infection.

[23] Multiple copulations are not necessary for reproduction, but may function to make the actual paternity of the female's offspring ambiguous.

[3] Occasionally, male olive baboons monopolize a female for her entire period of probable conception.

[3] One theory for why immature females tend to seek out infants is that they can prepare for their future roles as mothers.

A "wa-hoo" call is made in response to predators or neighbouring groups at night and during stressful situations.

[27] Other vocalizations include "broken grunting" (low-volume, quick series of grunts made during relatively calm aggressive encounters), "pant-grunts" (made when aggressive encounters escalate), "shrill barks" (loud calls given when potential threats appear suddenly), and "screams" (continuous high-pitch sounds responding to strong emotions).

[14] "Ear flattening", "eyes narrowed", "head shaking", "jaw-clapping", lipsmacking, and "tongue protrusion" are used when baboons are greeting each other, and are sometimes made with a "rear present".

[14] A submissive baboon responds with displays such as the "fear grin", the "rigid crouch", and "tail erect".

[28] The diet typically includes a large variety of plants, and invertebrates and small mammals, as well as birds.

[29] The olive baboon eats leaves, grass, roots, bark, flowers, fruit, lichens, tubers, seeds, mushrooms, corms, and rhizomes.

[29] Corms and rhizomes are especially important in times of drought, because grass loses a great deal of its nutritional value.

[29] In dry, arid regions, such as the northeastern deserts, small invertebrates like insects, grubs, worms, spiders, and scorpions fill out its diet.

[29] The olive baboon also actively hunts prey, such as small rodents, birds and other primates.

[5] Its limit is usually small antelope, such as Thomson's gazelle, but will also kill sheep, goats, and chickens from farms, which may amount to around one third of its food from hunting.

[30] In a field study, such behaviour was observed as starting with the males of one troop and spreading through all ages and sexes.

[30] In Eritrea, the olive baboon has formed a symbiotic relationship with that country's endangered elephant population.

Like most other baboon species, it is routinely exterminated as a pest for crop raiding and small livestock predation.