The sustainability of complex resource systems, such as the food, water, and energy (FWE) nexus, is increasingly threatened by climate change impacts, expanding populations, urbanization, and economic instability. However, while research on the topic has burgeoned, studies focused on solution development and implementation, especially at the urban level, have lagged behind. Against this background, we review the urban FWE nexus literature. We focus on the operationalization of solutions for implementation, and seek to identify opportunities for participatory approaches. Our results suggest that operationalization would benefit from: (1) more fully integrating urban social complexity; (2) extending our understanding of the nexus to include social responses to the impacts of interventions; and (3) ensuring that projects build knowledge that is not only actionable, but also credible, salient, and legitimate. We then discuss the potential of local, transdisciplinary approaches, in the form of urban laboratories, to shift the focus of FWE nexus research towards operationalization. We conclude with five recommendations: (1) knowledge development should extend to implementation; (2) stakeholders should be engaged, and be able to align solutions with the agency to implement; (3) research should move beyond material flows, and focus on the behaviors, habits, and social patterns that underpin urban complexity; (4) FWE nexus thinking should become part of participatory/laboratory approaches; and (5) policymakers should integrate nexus research into municipal strategies and plans.