The objectives of this study are to present a model for linking two intersecting areas—geopolitics and marine spatial planning (MSP)—thereby facilitating the democratisation of this debate and elucidating its significance as a foundation for strategic presence. MSP encompasses the incorporation of international treaties and agreements through MSP/UNESCO. In the Brazilian context, a multitude of related policies are already in progress. This study aims to explore how the mechanisms of this new green management model will operate following the approval by the Brazilian National Bank for Economic and Social Development (BNDES) of the investment for the Pilot Project on MSP in Brazil, which is based on preliminary studies conducted in the southern region of the country. Adopting a qualitative approach, the content analysis technique is employed to primary and secondary sources concerning the geopolitics of the South Atlantic and Brazil’s MSP. The analysis of the Brazilian case is justified by the country’s scale and its marine spaces, with policies currently in the implementation phase, indicating its commitment to sustainable development within the context of Brazil’s geopolitical position in the South Atlantic. The results of the analysis suggest that Brazil perceives MSP as a crucial mechanism for enhancing its leadership in the preservation and sustainable use of oceans, aligning with its broader strategy to consolidate its position within the geopolitical landscape of the South Atlantic.