This article examines republicanism in Brazil, addressing its historical evolution and practical application in the country’s political institutions. The study investigates how positivist and liberal currents influenced the transition to the Republic in 1889 and how republican principles, such as the common good and the separation of powers, are expressed in Brazilian democratic institutions. The aim is to understand republican theory in Brazil and analyze the impact of the judicialization of politics on the separation of powers. The methodology involves a bibliographic review and documentary analysis. The results indicate that, although Brazil formally adopts republican principles, significant challenges remain for their practical implementation. Institutional fragility, endemic corruption, and the judicialization of politics create barriers to the full realization of the ideals of the common good and civic participation. The study concludes that strengthening democratic institutions and combating corruption are essential elements to consolidate republicanism in Brazil and ensure it remains true to its fundamental principles.