Urban environments contain and are part of a wide range of interconnected complex systems, including infrastructures and services. Rapid and often uncontrolled urbanization triggers distributive inequities and environmental injustices, posing urgent and interconnected challenges that demand inter- and transdisciplinary solutions. Despite architecture’s commitment to ‘sustainability’, its central role in urban systems and their dynamics as well as the discipline’s intersections with other disciplines remain relatively little explored. In this contribution, we focus on the water–energy–sanitation (WES) nexus in Brazil, drawing from transdisciplinary workshops, scoping reviews, and systems mapping. We propose a framework for the analysis of urban nexuses. This framework builds on transdisciplinary systems mapping for the identification of nexus components, nodes, and their interconnections. Our findings indicate that a nexus perspective allows us to identify challenges in urban nexuses, productive intersections with the knowledge and approaches from other disciplines, and possible solutions in collaboration with non-academic stakeholders. We advocate for an expanded professional field and a redefined sense of responsibility within the discipline.