The Sustainable Development Goals (SDGs), Agenda 2030, and international law interact in multifaceted and complex ways. On the one hand, neither Agenda 2030 nor the SDGs fundamentally question the role of the international economic system, which is entrenched in international law and supportive of activities that do not necessarily further sustainable development. On the other hand, Agenda 2030 aims to transform our world, by evoking a bold cosmopolitan understanding of sustainable development, so that no one is left behind. This cosmopolitan understanding of sustainable development should inspire the application and development of international law, if indeed no one is to be left behind. International law offers ample opportunities for implementing such an approach to sustainable development.