Brazil and Angola are two regional powers that have in common the sharing of the South Atlantic, on opposite continental sides (South America and Southern Africa) and the fact that they are two Portuguese-speaking countries that have a geopolitical community, formed by nine states and spread over four continents and three oceans. Both are members of the South Atlantic Peace and Cooperation Zone, created in 1986 by resolution of the United Nations General Assembly, bringing together South American and African coastal states. In addition to having vast exclusive economic zones and continental shelves (in the process of expanding), the two countries are responsible for the rescue operations of a significant part of the South Atlantic, which is also home to most of its energy resources (offshore), on which much of its economy depends. The conjunction of the entry into force of the United Nations Convention on the Law of the Sea, in 1994, which conferred jurisdiction and sovereignty to coastal states over the contiguous maritime space and the liberalisation of world trade in goods, relaunched in 1995, with the creation of the World Trade Organization, increased the geopolitical and geostrategic relevance of the South Atlantic. Brazil has its main regional market in Mercosur, while the BRICS constitute its gateway to the global market. Angola is part of Southern African Development Community and the Economic Community of Central African States, in addition to being present at the Gulf of Guinea Commission and the International Conference on the Great Lakes Region, two particularly unstable regions in the field of maritime (piracy) and territorial security, respectively. The main research question is what is the geostrategic potential of Brazil and Angola in the field of the security of the South Atlantic? Under the theoretical lens of historical institutionalism and using a qualitative methodology, this chapter analyses the bilateral and multilateral cooperation between the two countries and concludes that depending on the political will of the respective leaders there are conditions for the institutionalisation of a productive political and military cooperation that promotes the security of that geopolitical space of the Atlantic.