Urbanization impacts public, wildlife and environmental health. Studies comparing rural and urban populations reveal negative effects of urban life on animal health, however, there is a paucity of research on its intra-urban variation. Specifically, whether body condition, body size and oxidative status of Neotropical birds varies with green space attributes in cities remains poorly understood, which limits strategies for healthier urban environments. In the city of Santiago (Chile), we compared body condition, body size and oxidative status between Rufous-collared sparrow (Zonotrichia capensis) that inhabit Urban Natural Remnants (UNRs) and urban parks and assessed the relationship of these variables with the vegetation attributes. We computed principal component analysis (PCA) for describing body condition, used tarsus length as body size indicator and measured the levels of lipid peroxidation (T-BARS) and total antioxidant capacity (TAC) for building an index of oxidative status (T-BARS/TAC ratio). We found that birds living in UNRs exhibited better body condition, larger body size and lower levels of oxidative stress than birds living in parks. UNRs providing greater woody plant richness promoted a better body condition and lower levels of oxidative stress in birds. Body size also increased with the percentage of shrub cover of the UNRs. These results evidence that body condition, body size and oxidative status of birds relate to green space type and vegetation attributes. These findings also highlight the importance of conserving UNRs, promoting shrub cover and prioritizing native plants in afforestation projects to build healthier urban environments for native birds.