The present paper aims at understanding the complex relationship between Brexit and secession by focusing on three aspects. First, it compares Article 50 TEU with constitutional provisions that allow for secession. Second, it explains the constitutional framework concerning the possible independence of Scotland and reunification of Ireland. Third, it discusses why a solution to the ‘Irish border’ conundrum that would entail a much closer relationship of this region with the EU than the rest of the UK should be seen as a pragmatic solution that protects the fragile balance struck by the Good Friday Agreement rather than as an annexation of Northern Ireland to the EU. As such, the chapter is a testament to the intertwined nature of the European constitutional landscape and the compound EU polity even in an area such as the one that deals with the withdrawal of a State from an international organisation; an area where States are supposed to possess almost unfettered autonomy.