The concept of heteronomy, as developed by Kant, has long remained underutilized in constitutional theory. The present article takes as its point of departure Kant’s transcendental formulation of the balance between autonomy and heteronomy as a crucial element in the safeguarding of individual freedom and the integrity of the constitutional order. Kant developed his argument in two stages. In the transcendental, ahistorical stage, he constructs autonomy as a form of self-binding to certain universal maxims, which renders his constitutional theory a duty-based one, in which moral autonomy amounts to self-heteronomy. At this juncture, Kant maintains his principled objection to constitutional heteronomy as reflected in his argument about majority-decision, his rationale for a system of separation of powers that ensures legislative supremacy, and his anti-paternalistic account of law. In the pragmatic, historical stage, Kant’s arguments appear to have been shaped by his engagement with the political developments of the late 18th century. The adoption of an anthropological mode of thought led his constitutional theory to evolve towards a form of coercive heteronomy. A number of paternalistic attitudes can then be identified, including Kant’s endorsement of monarchy as a superior route to republicanism, his argument for constrained republican representation without universal right to vote, and his opposition to the right to resist oppression. While this article aims to provide an internal critique of Kant’s theory of constitutional heteronomy, it also underscores the timeliness of his contribution to the field, as it sheds early light on one of the formative dilemmas that continues to plague liberal constitutionalism today.