Harvey’s Duiker occurs in lowland and montane forests, isolated forest patches, riverine forest, coastal scrub, thickets and other habitats with thick cover (East 1999, Kingdon and Rovero 2013). Occurs to elevations above 2,400 m in some Eastern Arc massifs (e.g., in the Ulugurus; Doggart et al. 2004).

Harvey's Duiker occurs in central and south-eastern Kenya, north-eastern and central Tanzania, marginally in southern Somalia, and northern Malawi, there is a single record from Zambia (Kingdon and Rovero 2013).

In Ethiopia an expedition to the Harenna forest in the southern part of Bale Mountains National Park in 1986 produced positive sightings of a “red” duiker. This was the first confirmed sighting of a Cephalophus duiker from Ethiopia. There has also been a subsequent sighting of this duiker in the same area. While identification of the species awaits confirmation, it is considered highly likely to be Harvey’s Duiker. This species occurs in southern Somalia and could possibly have entered the Bale forests up the Juba and Genale valleys, a route which has been used by forest primates. In 1996, the presence of an unidentified species of red duiker was confirmed in dense bush around and north of the headquarters of Omo National Park in the south-west. The Omo population could be Weyns’s Duiker (C. weynsi), which occurs nearby in the Imatong Mountains of South Sudan 400 km to the south-west (East 1999, Wilson 2001, Kingdon and Rovero 2013).

It is well represented in several protected areas, including Aberdares and Mount Kenya National Parks and Shimba Hills, Tana River, Arabuko-Sokoke, Boni, Dodori, National Reserves (Kenya), Mount Kilimanjaro, Udzungwa Mountains, Mikumi, Arusha and Lake Manyara NPs (Tanzania) and Bale Mountains NP (Ethiopia) (Kingdon and Rovero 2013).

There is a need for further taxonomic work to investigate the status of this species relative to Natal Red Duiker.