Background Inherent in the concept of ‘planetary health’ is that human and Earth’s health are inseparable and mutually dependent. Systemic change is needed to ensure a future where the needs of all people are met, equitably, within the means of the living planet. This depends on our comprehension of the interlinkages between people and planet and policies that address health, social and ecological wellbeing simultaneously – a process referred to as ‘multi-solving’. Cities globally are home to an ever-increasing share of the world’s population, and disproportionate contributors to both ecological degradation and unequal distributions of health-promoting goods and services. This makes them crucial partners for progress.

Methods In 2022, Glasgow launched a multidisciplinary, intersectoral university-city collaboration serving as a ‘living lab’ for urban system transformation. One component of this project involves public health academics, environmental scientists, quantitative modellers, and city stakeholders co-leading interdisciplinary systems science research. This has so far incorporated analysis of policy documents, visioning and participatory systems mapping workshops with stakeholders and communities, development of local thriving metrics, indicators and data, computational modelling and initial attempts to embed agreed health, social and environmental thriving ambitions in cross-sectoral policy practice.

Results Significant buy-in is required from a diverse range of cross-sector and multidisciplinary stakeholders, and we found that an iterative process of generating and then applying a multi-dimensional outcomes framework at the city scale was able to serve three functions, (1) as an effective tool for engaging stakeholders in dialogues for understanding the city’s health, social and ecological challenges and impacts; (2) as a locally-informed ‘compass’ by which city changemakers can develop and prioritise goals and actions and (3) making visible synergies, conflicts and possible mis-alignments between the diverse goals and actions in existing strategies.

Discussion Policymakers internationally are increasingly looking for and trialling approaches that go beyond ‘economic growth’ to bring health, social, and ecological values into decision-making. To our knowledge, this is the first study to use public health-led systems science in a real-world policy environment. The methods presented here at the city scale provide a first step in understanding connectivity that may lead to whole-system solutions for human and planetary health.