Smart city development is expanding rapidly globally and is often argued to improve urban sustainability. However, these smart developments are often technology-centred approaches that can miss critical interactions between social and ecological components of urban systems, limiting their real impact. We draw on the social-ecological-technological systems (SETS) literature and framing to expand and improve the impact of smart city agendas. A more holistic systems framing can ensure that ‘smart’ solutions better address sustainability broadly and extend to issues of equity, power, agency, nature-based solutions and ecological resilience. In this context, smart city infrastructure plays an important role in enabling new ways of measuring, experiencing and engaging with local and temporal dynamics of urban systems. We provide a series of examples of subsystems interactions, or ‘couplings’, to illustrate how a SETS approach can expand and enhance smart city infrastructure and development to meet normative societal goals.