This article examines the extent to which the European Court of Justice (ECJ) in its interpretation of EU Private International Law (PIL) rules purposively implements principles and values of EU integration and thereby constitutionalises these rules. To this end, possible vectors of constitutionalisation, such as the quest for autonomy, the mutual trust principle, market integration and fundamental rights are scrutinised. The article concludes that, despite topical examples, there is, as of yet, no pervasive constitutional reading of EU PIL. By applying its characteristic techniques of EU law interpretation also in this field, the ECJ further communitarises the practice of private international law. It thereby underlines, and builds upon, the fact that PIL in the EU Member States has become EU law. The future pertinence of the constitutionalisation label, however, will turn on whether the constructive reading of EU PIL provisions effectively implements genuine constitutional principles of the European legal order.