Adapting to a warmer world has become a priority, particularly in cities that have both large populations and exposure conditions exacerbated by the urban heat island effect. These cities are also committed to improving air quality. This article summarizes and discusses the main findings on the value of urban greening as a tool for preventing the health impacts of heat and on the associated potential benefits, particularly regarding air quality. The literature shows that vegetation can create cooling islands in cities and locally reduce temperatures and concentrations of certain air pollutants. Few epidemiological studies have examined the potential health impacts, but they suggest that vegetation likely has a protective effect on mortality and healthcare utilization during heat waves. Green spaces can also help restore and build people’s resilience and reduce the health impacts of heat and pollution. Current knowledge allows for the development of tailored greening strategies to optimize benefits in terms of reducing urban heat islands, improving thermal comfort in winter, and enhancing air quality. The associated health benefits are potentially significant. Only a portion of these can be quantified using current health impact assessment tools.