Land-use change is considered a major driver of biodiversity loss. In the western part of the Tarangire–Manyara ecosystem, we assessed large mammal species richness along a land-use gradient (national park, uninhabited pastoral area and settled pastoral- and farmland). We found the highest species richness in the national park and in the pastoral area and lowest species richness in the settled and farmed area. There was little evidence of seasonal changes in species diversity. Except for top-order carnivores, all functional feeding guilds were still represented in pastoral and settled areas. Although we did not find significant differences in body mass distributions and species’ representation of feeding guilds between the study sites, there was a trend that omnivores, mesopredators and top-order carnivores tended to occur at lower species richness in agricultural areas than in the pastoral and fully protected areas. These results indicate that areas used for livestock keeping can maintain high wildlife species richness and that direct and indirect effects of agricultural and settlement expansions are the main drivers of species richness loss in the Tarangire– Manyara ecosystem and possibly other African savannah ecosystems. These results are useful for informed land-use planning that aims to maintain species diversity and ecological connectivity between protected areas.