The twenty-first century has witnessed a profound reshaping of global geopolitics, driven primarily by the rise of China as a dominant global player. Within this transformative context, this chapter scrutinises Brazil’s evolving foreign policy within the BRICS bloc under two distinctive presidential administrations: Luiz Inácio Lula da Silva and Jair Bolsonaro. The central research query guiding this chapter is: How did the Lula and Bolsonaro administrations adapt Brazil’s engagement with BRICS to navigate the changing dynamics of global geopolitics, with a specific focus on BRICS’ role in shaping Brazil’s post-Atlantic foreign policy orientation? This research sheds light on the pivotal role played by BRICS in Brazil’s foreign policy stance in the emerging post-Atlantic geopolitical landscape. It underscores BRICS as a linchpin in Brazil’s foreign relations, especially in managing its multifaceted partnership with China. Furthermore, this chapter contributes to understand the intricate interplay between regional and global dynamics, offering insights into Brazil’s agency in shaping BRICS’ collective response to the evolving global power dynamics. Methodologically, a comparative analytical framework guides this chapter’s examination of Brazil’s strategies during the Lula and Bolsonaro presidencies. A broad spectrum of primary and secondary sources, encompassing official government documents, speeches, diplomatic accords, and scholarly literature, informs the elucidation of Brazil’s journey in its partnership with BRICS and the ramifications for its post-Atlantic geopolitical position. This comparative approach provides insights into the persistence of Brazil’s foreign policy across different political administrations. The chapter underscores how the Lula and Bolsonaro governments harnessed BRICS as an important platform to advance Brazil’s global interests. By doing so, this chapter contributes to a nuanced understanding of BRICS’ role as a transformative force in shaping the foreign policy of its member states, particularly Brazil, in the twenty-first century. In summary, this chapter adds to the ongoing discourse on the evolving dynamics of global geopolitics by highlighting BRICS’ pivotal role in shaping Brazil’s post-Atlantic foreign policy orientation. It offers a comprehensive analysis of how Brazil, under the stewardship of Lula and Bolsonaro, leveraged BRICS as a strategic instrument to navigate the changing global power dynamics and underscores the significance of collective action within this alliance in defining the new contours of international relations.