The engagement of conservative, populist governments with constitutional reform and constitution-making is perceived as a significant threat to the rule of law and democracy within the European Union. Constitutionalists often assume a relation of mutual exclusion between populism and constitutionalism. In contrast, I argue that while populism ought to be understood as a rejection of liberal constitutionalism, it equally constitutes a competing political force regarding the definition of constitutional democracy. The article first discusses populist constitutionalism in the context of the two, main modern constitutional traditions: the modernist and the revolutionary ones. Second, I discuss the populist critique of liberal constitutionalism, with a central focus on the recent cases of right-wing populism in power in East-Central Europe. Four dimensions are prominent: 1) popular sovereignty as the key justificatory claim of populism; 2) majority rule as the main populist mode of government; 3) instrumentalism as the legal-practical approach of populists; and 4) legal resentment as the populists’ main attitude towards public law. In conclusion, I argue that while the populist critique of liberal constitutionalism provides significant insights into structural problems of liberal democracy, populist constitutionalism ultimately fails to live up to its own democratic promise.