Abstract Tropical rainforests including high mountains are the most diverse terrestrial ecosystems. The ecology of tropical insects has been documented, but there is still a knowledge gap on insect diversity within certain underexplored regions such as the Afrotropical Mountains. A study was conducted in Nyungwe National Park, Rwanda, an Afromontane tropical rainforest and a biodiversity hotspot. The aims of the study were to assess (1) the fruit‐feeding butterfly species and their distribution across an elevation gradient in Nyungwe; (2) the elevation distribution range of each fruit‐feeding butterfly species; and (3) the effect of seasonal variation on fruit‐feeding butterflies' distribution across an elevation gradient in Nyungwe National Park. Stratified seasonal sampling was conducted using fruit‐baited traps along an elevation gradient spanning from 1700 to 2950 m of altitude. Fifty‐six species including 10 Albertine Rift endemics were recorded, and 77% of the recorded species range between 1700 and 2100 m of altitude. Higher species richness and abundance were recorded during the dry season and decreased with increasing elevation. This study contributed to the knowledge of Nyungwe butterflies' diversity and provided baseline data for use in future monitoring of climate change effects in high mountain tropical rainforests within the Albertine Rift region.