In the European Union, borders are largely communitised. With the creation of the European Border and Coast Guard standing corps, their Europeanisation has reached its temporary climax in the expansion of the Frontex mandate decided in 2019. This standing corps of 10,000 Frontex border guards (until 2027) is to be used for border controls, repatriations and work against human trafficking. For the first time, the European agency not only receives extensive resources, but also executive powers at the external borders of the European Union. The creation of the standing corps marks a paradigm shift in the European Union – it means the de facto establishment of a European border police. This border police is uniformed, armed, and has genuine border police tasks and executive powers previously reserved for the bodies of European nation states. Theoretically, this milestone of deepening Europeanisation can be classified as the result of supplementary institutionalisation. How the standing corps is formed, with which discourses and symbols the establishment of the border police is accompanied, and why it can be understood as supplementary institutionalisation, is the subject of this contribution.