This working paper analyses the relationship between the European Union and the G20, with an emphasis on how the two bodies have impacted and shaped each other’s agendas. Both entities mark, in very different ways, a changing world order in which states are cooperating ever more closely in order to tackle transnational challenges. However, the relationship between both entities deserves more attention. In this working paper, both the representation of the EU (and its Member States) at the G20 and the impact of G20 decisions on EU legislation are analysed. We argue that the relationship between both organizations is at the same time problematic and symbiotic. Symbiotic as the EU has influenced the functioning of the G20 while the G20 agenda has itself had an impact on EU legislation. It is problematic in the sense that the EU is arguably over-represented in the G20, and there is little in the EU’s treaties to guide the relationship between the EU and global processes such as the G20.