The geographical area located in South America, on the borders of Argentina, Bolivia, and Chile, known as the “Lithium Triangle,” holds over 85% of the world’s reserves of this soft metal. Meanwhile, Brazil holds about 1% of the world’s lithium reserves in its “Lithium Valley.” However, the greatest impact of the exploitation of this commodity is related to its contemporary incorporation into the productive systems of some of the most advanced economies in the world. Therefore, we advance the following research questions: How are the South American countries of the Lithium Triangle positioned in the global lithium market, particularly in relation to the geoeconomic strategies of China and the United States? And specifically, what is Brazil’s current and prospective geoeconomic importance in the lithium market? From a methodological point of view, this chapter will triangulate data and information from South American lithium-producing countries; advanced economies, especially the USA and China; and regional organisations, such as CEPAL. Data analysis shows that the United States, China, and other countries such as Canada and Japan are actively and strongly involved in securing new lithium sources from the “Lithium Triangle” and the “Lithium Valley,” a key element in the global economy’s transition from fossil fuels to renewable energy, thus operating a significant increase of the geoeconomic importance of the leading lithium producers in South America (Argentina, Bolivia, Brazil, and Chile).