RESUMO: Urbanization is a key driver of biodiversity change globally, reshaping species composition, ecosystem functions, and spatial diversity patterns. In this study, we investigated how urbanization influences the taxonomic and functional beta diversity of dung beetles in the eastern Amazon. Sampling was conducted along a preserved–rural–urban gradient using baited pitfall traps during the rainy season. We focused on three functional traits closely linked to dung beetle ecosystem functions and characterized landscape structure around each site using four land-use and land-cover types. Taxonomic and functional beta diversity, along with their replacement and gain/loss components, were calculated and related to urbanization effects. In total, we collected 4298 individuals from 66 species, with both richness and abundance declining from preserved to urban sites. A nested pattern in taxonomic diversity and evidence of nested functional diversity emerged along the gradient, suggesting that urbanization acts as a filtering process that progressively excludes species with unique trait combinations. Functional differences among environments were largely driven by nestedness, indicating that urban assemblages represent subsets of species from less disturbed habitats rather than functionally distinct assemblages. Additionally, the positive relationship between environmental dissimilarity and taxonomic beta diversity underscores the influence of landscape changes across the gradient on dung beetle assemblages. Our results demonstrate that urbanization reduces both taxonomic and functional beta diversity in Amazonian dung beetles, reinforcing the importance of conserving forest cover. Implementing sustainable policies, such as protecting urban forest remnants, can help preserve biodiversity and the ecosystem processes it supports within tropical cities.