Confined to savanna grasslands, open bushlands, and woodlands (Cumming 2013). Although usually absent from forests, thickets, cool montane grasslands, deserts, and succulent steppes, the Common Warthog occupies forested areas in parts of eastern Africa; Goda Mts. in Djibouti), Bale Mts. In Ethiopia, and Mathews Range in Kenya (Yalden et al. 1996, Künzel et al. 2000, Cumming 2013, L. Borgesia pers. comm. in Butynski and De Jong in prep.). Recorded to 3,500 m asl on Mt Gaysay, Ethiopian Highlands (Waltermire 1975, in Yalden et al. 1996).  

Dependent on perennial surface water at some sites (Estes 1999, Meijaard et al 2011, Cumming 2013), but drinking water not essential at other sites (Dorst and Dandelot 1970, Skinner and Smithers 1990, De Jong and Butynski 2014, Butynski and De Jong in prep.). In north Kenya, low densities of common warthog occur in sub-desert where drinking water is absent for several months of the year (De Jong and Butynski 2014).

Generally diurnal but sometimes active at night in West Africa, Kenya, and Zimbabwe (Cumming 1975, De Jong and Butynski 2014). This is likely an adaptation to avoid the hottest hours of the day, humans and other diurnal predators, and competition for water and food (De Jong and Butynski 2014).

The Common Warthog is widely distributed over sub-Saharan Africa, occurring in scattered populations in West Africa eastwards to Eritrea and Ethiopia, southward through eastern Africa, and over much of southern Africa to southern Angola, Botswana, and Mozambique to northeast South Africa. Historically, the common warthog was not present in the arid Karoo of South Africa where the extinct Cape (desert) warthog Phacochoerus aethiopicus aethiopicus was present (Cumming 2013). Expansion of the Sahel-zone has resulted in a marked contraction in the range of the common warthog since at least the early 1980s. J. Newby (pers. comm. in Vercammen and Mason 1993) reported the extinction of the species in Niger but then notes their persistence in south-central Aïr Mts., Niger. (J. Newby pers. comm. in Cumming 2013). In addition, P. africanus were photographed in 2014 in W National Park, southwest Niger (C.T. Hash pers. comm.).

The common warthog is expanding its geographic range in South Africa (Nyafu 2009).

Sympatric with the Somali (desert) warthog (Phacochoerus aethiopicus delamerei) in north Somalia, and central, east, and southeast  Kenya (De Jong and Butynski 2014, De Jong et al. in prep.).