Scaling up urban agriculture could leverage transformative change, to build and maintain resilient and sustainable urban systems. Current understanding of drivers, processes and pathways for scaling up urban agriculture, however, remains fragmentary and largely siloed in disparate disciplines and sectors. Here we draw on multiple disciplinary domains to present an integrated conceptual framework of urban agriculture and synthesize literature to reveal its social–ecological effects across scales. We demonstrate plausible multi-phase developmental pathways, including dynamics, accelerators and feedback associated with scaling up urban agriculture. Finally, we discuss key considerations for scaling up urban agriculture, including diversity, heterogeneity, connectivity, spatial synergies and trade-offs, nonlinearity, scale and polycentricity. Our framework provides a transdisciplinary roadmap for policy, planning and collaborative engagement to scale up urban agriculture and catalyse transformative change towards more robust urban resilience and sustainability.