The Brazilian Amazon is under threat from more frequent and intense forest fires, with a few studies showing negative consequences for forest integrity and the biodiversity. However, the impacts of this disturbance on tropical forests remain mostly unknown. We investigate the impacts of forest fires on community parameters and biomass of dung beetles, a cost-effective indicator of disturbance and overall biodiversity, in the northern Brazilian Amazon. Our results indicate that burned forests harbor a modified dung beetle community, with altered abundance, community composition, and structure. Burned forest samples had lower total biomass and were dominated by small-bodied dung beetles. Large-bodied tunneler species were negatively impacted, responding to changes in environmental characteristics such as soil compaction. Lower biomass and higher predominance of smaller species in burned forest is likely to impact dung beetle-mediated ecological functions, such as nutrient cycling and seed dispersal. Our results support that forest fires in the Brazilian Amazon pose a serious threat to local biodiversity and habitat integrity.