Urbanisation and climate change are urging cities to chart novel paths towards sustainable futures. Many cities are turning to the alluring 'circular economy' (CE) concept to guide this redirection. The CE concept re-imagines how flows of resources moving through economies might be 'closed'. Here, we explore this new 'circular city' agenda by asking: How are cities adopting CE as a strategy?. We found that political leadership, building adaptable future visions, using experimental approaches (such as living labs), developing contextual knowledge about resource use, and engaging with diverse stakeholders to be important. However, we also expose that there is a lack of consensus on what a circular city constitutes and a need to further untangle the how and why of the circular city concept. The research contributes to the field by outlining emergent cases, identifying a set of common policy strategies, conceptualising a circular city and identifying areas for future research.