Urban transformation research forms an emergent interdisciplinary field with open boundaries that combines complex system studies and urban studies. It explores patterns and dynamics of change linking cities and diverse socio-technical and social-ecological systems across levels and scales, and develops new forms of intervention to foster their sustainability. This paper identifies and maps out the current status in this field and derives strategic recommendations for future research. It delineates a spectrum of recurrent epistemologies concerned with either system change, urban change or urban/system interactions, linked to an emphasis on urban metabolism, resilient communities and ecosystems, grassroots innovations or urban innovation systems. Moreover, seven key factors co-shaping urban transformations are recognized (agency, politics, capacity, policy, experiments, foresight and geography). To better exploit potential synergies between existing strands and address gaps in the light of imminent urban sustainability challenges, future urban transformation research should (1) Share a relational geographical perspective that connects the above epistemologies; (2) Identify and engage with the spatial-institutional challenges of urban transformations; (3) Move towards multi-system approaches linking various sectors and domains; and (4) Focus on transformative capacity and its agency components as an empowering lever for systemic urban change.