In ectotherms, the color of an individual's cuticle may have important thermoregulatory and protective consequences. For instance, the thermal melanism hypothesis predicts that cooler environments, often at higher altitudes and latitudes, favor darker individuals with more melanin, while the photo-protection hypothesis suggests that higher levels of melanin are able to protect against harmful ultraviolet radiation. These potential mechanisms have been widely supported by numerous studies on insect coloration and used to explain the geographical variation in body color among insect communities in natural habitats. Due to human activities, the microclimatic conditions in urban habitats often differ significantly from those in adjacent natural habitats. However, the predictability of body color variation in urban insect communities and the potential drivers remain unknown. We examined the ecological response of cuticle lightness in urban ants (Hymenoptera: Formicidae) to regional variations of temperature and UV-B condition. Using pitfall traps, we sampled 55,890 ground-foraging worker ants (81 species from 31 genera) from 64 urban and suburban sites across eight counties over a broad elevational range of 510-3380 m (a. s. l.) along the eastern margin of the Qinghai-Tibetan Plateau. Cuticle lightness of worker ants for each species was extracted from microscope photographs, which were further used to evaluate the community brightness in the ways of community-weighted mean and community mean. We used one-way ANOVA to assess whether the significant differences in ant community brightness existed among counties, and performed linear mixed-effects models to test the potential effects of regional temperature and UV-B on cuticle lightness of urban ant communities. We found that cuticle lightness of urban ant communities significantly differed across counties (e.g., the average values of community-weighted mean and community mean were approximately 39% and 32% higher in Yuanmou than those in Ganzi, respectively). Cuticle lightness of ant communities was greater in the regions with higher temperature, aligning with the thermal melanism hypothesis. However, the effect of regional UV-B radiation was not significant, which could not be explained by the photo-protection hypothesis. Our study highlights the sensitivity of cuticle lightness response in urban ant communities to regional temperature variation, and that urban landscapes may mediate the impacts of regional UV-B conditions on cuticle lightness of ant communities. Therefore, studies using animals with melanin-based colors as a model for the ecological response mechanisms in the context of climate change would facilitate to predict future evolutionary trends in urban biodiversity and inform the development of urban management strategies.