Cities are complex systems with interactions between various factors e.g.: urban density, ‘green’ infrastructure and open space, housing, transport, waste management, water and sanitation, air quality, health systems, and city governance. With an increasing majority of the global population now inhabiting urban areas, it is essential that cities reduce their environmental footprints and increase their resilience to environmental change whilst protecting and promoting planetary health. This special issue seeks to explore how cities can address the multiple challenges of health and sustainability. This involves the development and implementation of evidence-informed solutions in a variety of different contexts (mature cities, rapidly expanding urban areas, shrinking cities, and informal settlements; Global North and Global South); political systems (high centralised, decentralised, autocratic, democratic) and scales (city, neighbourhood, street, building). Papers are sought on a variety of topics that model, track or evaluate the effectiveness and outcomes of different policies or practices, as well as the interaction between various systems. Evidence is sought from different contexts from which we expect distinctions, complementarities and comparisons to be drawn for informing equitable development pathways for improving sustainability and public health in cities. In particular, we are interested in research that accelerates the implementation of large-scale ‘transformational’ changes that improve health and sustainability in low-, middle- and high-income settings, and across different socioeconomic and demographic groups. Papers in this special issue address key urban topics including but not limited to: Systematic/scoping reviews of evidence on potential solutions for healthy sustainable urban development; Methods for tracking progress towards city-specific sustainability and health goals, and/or studies that compare city development trajectories; Modelling or evaluation of urban health and wellbeing, including: energy provision, transport infrastructure and operation, green and blue infrastructure, climate, air pollution, emissions, health systems, housing, water, sanitation, and waste management; Behavioural science, systems thinking and participatory methods to inform and develop intervention strategies and/or understand processes for implementing change; Public engagement and capacity building; Studies into the use of research evidence on sustainability and health by decision-makers and other stakeholders in public policy; Studies into the effectiveness of methods of dissemination, communication and engagement to help drive change; How health systems identify and reduce risks of disease and epidemics in urban planning and infrastructure; Policy analysis of health intentions/outcomes in the regulation of urban infrastructures; Theories of change for sustainability and health.