By 2050, 70% of the human population will reside in cities. The climate crisis increasingly threatens city healthcare systems, infrastructure, and residents. Climate change directly and indirectly impacts the functioning of health care systems—which also contribute to environmental and climate hazards through medical waste, pollution, and greenhouse gas emissions. Both health care systems and city planners have critical roles in addressing climate impacts. In addition to providing medical care and counselling for climate-related issues, health care systems can expand into roles as anchor institutions and resilience hubs to support climate readiness efforts. Cities can champion such efforts while also employing policy and infrastructure approaches to create climate-ready cities that support residents’ health and urban healthcare institutions. While health care systems and cities can make independent progress toward climate adaptation, mitigation, and resilience, their interdependencies call for increased exploration of collaborative approaches. In this article, the authors outline the impacts of climate change on health care systems and cities and provide a strategic overview of what health care systems and city leaders can do to address climate change. They provide examples of practical solutions, underscore the importance of data and their role in protecting urban populations, highlight potential challenges, and suggest a path forward for cities and their health care systems.