Ecological data in protected areas are crucially important for improving management effectiveness and policy decision. Hence, this study was conducted to determine the diversity, abundance and distribution of mammalian species across major habitat types (i.e. Montane Forest, Wooded Grassland, Woodland and Riverine Forest), and between dry and wet seasons in Chebera Churchura National Park (CCNP), Ethiopia. We tested the hypothesis that the diversity and population dynamics of mammalian species in CCNP vary across habitat types and between seasons due to differences in availability and heterogeinty of resources. We counted mammals along with sighting distance transects across habitat types, both in wet season and dry season, using the naked-eye and a 8 × 40 Bushnell® binoculars. We recorded a total of 19 mammalian species in the CCNP, including the endangered African Elephant (Loxodonta africana), the Vulnerable Leopard (Panthera pardus), Lion (Panthera leo), and the Near Threatened African Buffalo (Syncerus caffer). We found a significant effect of habitat types (P<0.05) on species richness, species composition, and population density of mammals, but the effect of season was non-significant. Species richness was highest in the Montane Forest (16 species), due to its dense tree canopy with multilayered structure, and diverse micro-habitatats, providing good protection. However, both Shannon diversity index (H: 1.88) and evenness (H’: 0.71) were highest in the Woodland habitat, with greater plant diversity, supporting mammalian species with varying feeding strategies. Riverine forest had the lowest richness (11 species), Shannon diversity index (H: 1.20), and evenness (H’: 0.50), due to its less vegetation cover, supporting low mammalian security and breeding sites. Our findings showed that CCNP an important conservation site for threatened mammalian species in Ethiopia, with diverse habitat types acting as drivers of mammalian diversity, abundance and distribution.