The nature of the global environmental crisis means that the related policies have to be multilateral, multi-actor, multilevel and multisite, creating a multiplication of institutional interactions. In this chapter, we use the concept of polycentricity to reflect on the latest evolution of the EU environmental competences, instruments and impacts with regard to this global environmental complexity. The analysis of these three elements shows how the EU navigates through environmental complexity, embracing a complementary role in a post-Paris Agreement landscape.