This chapter discusses the concept of data-driven regulation and governance in the context of smart cities by describing how these urban centres harness these technologies to collect and process information about citizens, traffic, urban planning or waste production. It describes how several smart cities throughout the world currently employ data science, big data, AI, Internet of Things (IoT), and predictive analytics to improve the efficiency of their services and decision-making. Furthermore, this chapter analyses the legal challenges of employing these technologies to influence or determine the content of local regulation and governance. This chapter explores in particular three specific challenges: the disconnect between traditional administrative law frameworks and data-driven regulation and governance; the effects of the privatization of public services and citizen needs due to the growing outsourcing of smart cities technologies to private companies; and the limited transparency and accountability that characterizes data-driven administrative processes. This chapter draws on a review of interdisciplinary literature on smart cities and offers illustrations of data-driven regulation and governance practices from different jurisdictions.