This article provides an overview of the juridical discourse that acted as a basis for the historical development of Brazilian illiberalism. Without setting aside the question of an inner tension between liberal and illiberal theories of Brazilian constitutionalism, but focusing primarily on antiliberal and illiberal positions, this article presents the leading theories of Brazilian constitutional scholars. It shows that the seeds of illiberalism were planted under the flag of a specific type of authoritarian constitutionalism, which was developed under different constitutions, but which mainly refers to the 1937 Constitution. It discusses the theories of movements such as integralismo, the legal thought of authors such as Francisco José Oliveira Viana and Francisco Campos, and concepts such as national security. The article also explores, under the 1988 Constitution, the authoritarian reminiscences that favored the structuring and diffusion of the current Bolsonarist illiberalism. Finally, it debates the chances for the endurance of illiberalism in Brazil and whether or not it could benefit from wider popular acceptance.