In recent years, the Smart City has become a very popular concept amongst policy makers and urban planners. In a nutshell, the Smart City refers to projects and planning strategies that aim to join up new forms of inclusive and low-carbon economic growth based on the knowledge economy through the deployment of information and communication technologies. However, at the same time as new urban Smart interventions are being designed and applied, insufficient attention has been paid to how these strategies are inserted into the wider political economy and, in particular, the political ecology of urban transformation. Therefore, in this paper we critically explore the implementation of the Smart City, tracing how the ‘environment’ and environmental concerns have become an organising principle in Barcelona’s Smart City strategy. Through an urban political ecology prism we aim to critically reflect upon the contradictions of the actually existing Smart City in Barcelona and how Smart discourses and practices might be intentionally or unintentionally mobilised in ways that serve to depoliticise urban redevelopment and environmental management. The paper stresses the need to repoliticise the debates on the Smart City and put citizens back at the centre of the urban debate.