In DR Congo, Weyns’s Duiker prefers large blocks of closed forest, both primary and older secondary, but avoids new clearings and swamp forests, as well as stands of monodominant Gilbertiodendron dreweri (Hart 2013). In the highlands of the Albertine Rift and East Africa, it occurs in submontane and montane forests up to 3,000 m (Hart 2013).

Most of the range lies within DR Congo, east of the Congo river, but extending north of the Ubangui R to the Albertine Rift and south to the limits of the rainforest in Maniema, Kivu and possibly northern Katanga province; distribution in the east is more fragmented, encompassing patches of lowland, submontane and montane forest in western Uganda, western Rwanda and Burundi, western Tanzania (Mahali mountains and Gombe), Mt Elgon, Kakamega forest and Mau Escarpment (western Kenya) and South Sudan (Imatong and Dongotona mountains) (Hart 2013). Also occurs in Chinko ecosystem of south-east Central African Republic.

This species occurs in a several protected areas, including the Okapi Faunal Reserve and Maiko and Salonga National Parks (DR Congo), Kibale NP (Uganda), Mount Elgon NP (Kenya) and Mahala Mountains NP (Tanzania) (East 1999). Populations in East African locations are at higher risk, especially in the isolated forest islands at the eastern edge of the range; at least one population in Nyungwe Forest, Rwanda, is suspected to be locally extinct (Hart 2013).