Urban health, including physical health and wellbeing, has gained global a ention as cities prioritize policies that promote healthier living. This study answers one central question: what are the health determinants resulting in diff erent health outcomes throughout a city? It seeks to identify critical determinants of underperforming health and wellbeing status from variables related to urban health. Using a case study based in London, this study applies a decision-tree model approach to identify determinants from three dimensions, i.e. environment, socioeconomics, and urban planning and design, to obtain the relative importance of these health and wellbeing determinants. This study bridges the gap between cutting-edge data science methods and urban health research, providing urban planners and decision-makers with data-driven evidence and a new tool to shape a healthier city.