Urbanization is known to be associated with deep and rapid environmental changes that may be a threat to biodiversity. In that context, urban exploiter species are relevant to study because they usually thrive in cities and their population trends can help us assess the impact of recent urban environmental changes on urban wildlife. Recently, the house sparrow (Passer domesticus), a typical urban exploiter, has shown drastic population declines in numerous cities, and previous studies have shown that young urban sparrows bear elevated corticosterone levels. We conducted a long-term experimental study to test if such early-life exposure to corticosterone could be involved in the decline of urban house sparrow populations. We experimentally manipulated developmental exposure to corticosterone of house sparrow chicks and examined the short- and long-term impacts of this manipulation on several organismal systems (endocrine axes, metabolism, behaviors) and performance metrics. Early-life exposure to corticosterone had detrimental impacts on multiple physiological and behavioral traits of this urban exploiter (growth, competitive and anti-predator behaviors, survival). Interestingly, it was also associated with long-lasting endocrine (HPA and HPG axes) and metabolic changes that may allow sparrows to cope to a certain extent with urban constraints, notably by adjusting individual stress-coping strategy, reproductive investment and metabolism to an urban way of life. Altogether, this integrative study supports the hypothesis that the detrimental impact of urbanization on house sparrow populations could be mediated by developmental exposure to corticosterone. It highlights that endocrine mechanisms may help us better understand how wild vertebrates are impacted by urbanization and environmental changes.