Habitat loss is a driver of decreasing biodiversity worldwide. Across the globe, native ecosystems are in contact with an urban matrix that expands endlessly with negative consequences for biodiversity. Butterflies are a charismatic group widely used for monitoring and conservation. Most butterfly species are strongly associated with specific habitats and ecosystems and are considered good biological indicators, allowing us to assess the impact of anthropogenic factors on biodiversity, at scales from microhabitats to landscapes. The study of urban butterfly ecology can be a valuable tool for planning sustainable cities; however, knowledge about the natural history, diversity and distribution of butterflies is still scarce. We present the “state of the art” on the community ecology of butterflies across urban gradients in tropical and subtropical sites, highlighting the effects of urbanization on biodiversity. We used robust datasets from two cities in Brazil (Campinas and Porto Alegre) to describe the effects of urbanization on the structure of butterfly assemblages. These cities probably have the more complete datasets in the tropics concerning the influence of urbanization on butterflies. Some groups of butterflies disappear from cities, and there are negative impacts of urbanization on diversity and effects on the composition of functional traits. Thus, it is already possible to suggest guidelines for the careful planning and management of city for the recovery of ecosystem services, the maintenance of biodiversity and the conservation of urban ecosystems, which play important roles in bringing people closer to nature.