The international political context of the 2010s proved to be very different from that of the beginning of the twenty-first century, when the middle powers and regional powers found a favourable scenario for growth, driven by the commodities boom and boosting of the global market, especially in China. Even with the repercussions of the 2008 crisis, the Arab Spring and the Euro Crisis, regional powers, such as Brazil, found it difficult to sustain economic growth and maintain a more autonomous international policy. In addition to the changes in the external scenario, the internal dynamics of Brazilian society (especially since 2013) and the demands of different political, economic, and social groups have also called for a review of Brazilian foreign policy, especially that directed toward the countries of the Global South. In South America, these constraints have been reflected in the political (with the end of the Pink Tide) and economic (with the growth of the Chinese presence and the creation of the Pacific Alliance) reconfiguration of the region, as well as transforming the very dynamics of regional integration and cooperation once led by Brazil. The aim of this chapter, therefore, is to analyse Brazil’s posture of regional leadership in South America, which gradually weakened over the course of the 2010s. The loss of political prominence and priority for the region was reflected in a regional disengagement that compromised Brazil’s articulation with its neighbours, changed the emphasis of regional agreements (such as MERCOSUR), and dismantled processes of understanding and historical negotiations that gave rise, for example, to UNASUR. In that sense, based on a qualitative analysis of primary sources (from institutions and governments) and a literature review, we set out to analyse the internal and external conditioning factors that led Brazil to revise its foreign policy toward South America during the Dilma Rousseff, Michel Temer, and Jair Bolsonaro governments. Using the theoretical-conceptual tools of Foreign Policy Analysis, we try to demonstrate that there was a gradual change of adjustments in Brazilian foreign policy that led to a change of objective and an attempt at international reorientation in this period. In the long term, these gradual changes resulted in Brazil’s disengagement from regional affairs, jeopardising the regional leadership position it had held since at least the 1990s.