The Canada Excellence Research Chair in One Urban Health acknowledges that cities are unique ecosystems with opportunities and challenges for the well-being and health of humans. With more than 50% of the population worldwide living in cities, many disciplines are engaged in analyses and interventions to make cities better places. The goal of this CERC is to merge the World Health Organization Healthy Cities social movement with the One Health approach that examines human-animal-nature disease interactions. By combining the social science and One Health approaches, this research program proposes new, engaged and integrated ways to develop healthier cities for all. This inclusive partnership based in Montréal will mobilize citizen science, social movements and old and new networks for cities, health and sustainability. The CERC in One Urban Health will reaffirm and strengthen the relationship between the human, animal and natural environment ecosystems, and how they achieve durable meaning.