This article outlines a critical systems theory approach to the study of populism by arguing that populism is an avenue of contestation which assumes a distinct role and function in the existing constitution of the political system. Most notably, it is characterised by the re-entry of a popular sovereignty dimension within regular political procedures. By taking up a critical systems theory perspective, it becomes possible to more precisely distinguish populism from other forms of politics, such as oppositional politics, social movement politics or procedural constitutional politics. Further, populism’s oscillation between democratic and authoritarian dynamics can be elucidated as an inversion which operates from within its political form. Finally, it is argued that the critical systems theory approach provides a more nuanced understanding of populism’s inherent problems and, consequently, moves beyond a blunt defence or rejection of populism as such.