Cities are central to achieving the 2030 Agenda for Sustainable Development, yet many remain disengaged from the process. This paper examines nine city and subnational pilot projects conducted between 2015 and 2019, to assess the role of a data-based approach to governance in improving decision-making for sustainable development. We consider to what extent a data-based approach to governance can help cities in (a) localizing the sustainable development goals (SDGs); (b) integrating national and local datasets; (c) increasing openness of data and enabling better accountability for outcomes; and (d) encouraging innovation in data gathering. We find that data is considered a useful entry point for local sustainable development conversations and employing a focus on data management is welcomed by nearly all local governments, however, few localities explicitly focus on data to improve their sustainable development outcomes. Critically, despite the excitement around big data, most cities are unable to access them due to capacity challenges, data ownership, and privacy concerns.