The mantled guereza is distributed throughout Equatorial Africa. It ranges from Nigeria and Cameroon in the west to Ethiopia, Kenya, Uganda, and northern Tanzania in the east. The mantled guereza lives in both deciduous and evergreen forests. It mainly inhabits forest and savannah woodlands and often extend into highland and montane forests. It can be found in other forest habitats, both primary and secondary, such as riparian (near fresh or brackish water), gallery, and upland forests. It is particularly common in forests close to rivers and lakes and at high elevations. It can be found in elevations as high as . This species prefers secondary forests and selects them over old-growth forests if given the choice. It is likely that the mantled guereza prefers these forests due to the increased number of food trees and the weaker chemical defenses of the species within. The mantled guereza is sometimes found in swamps as well as human-made habitats such as Eucalyptus plantations, which may be frequented when the monkey has nutritional deficiencies.
