The South Atlantic Ocean has gained a growing geostrategic importance due to its abundant natural resources, biodiversity, and critical trade routes, attracting interest from both regional and extraregional powers. However, it remains underexplored in academic literature. While aiming to contribute to security studies, this chapter examines how the maritime security strategies implemented by Brazil, China, and the European Union have shaped South Atlantic geopolitics from 2006 to 2022. To this end, it engages with these actors’ foreign policy decisions related to their international power projection by analysing a series of official strategic documents. Such analysis offers insights into their capacity to address potential security challenges, safeguard their strategic interests, and influence the region’s stability and geopolitical dynamics. The findings suggest that Brazil has attempted to achieve regional prominence by fostering closer relations with South Atlantic countries and adopting multilateral policies to deter extraregional actors. On the other hand, China and the European Union have expanded their presence, challenging Brazil’s dominant regional position, particularly in maritime security. Moreover, China has taken a geostrategic and economically oriented approach, while the European Union has exerted influence through maritime governance policies.