This article examines South–South relations by exploring the South American experience. Emerging from the rise in leftist political movements at the turn of the millennium, the region engaged in a broad range of initiatives to address economic and security concerns. By excluding the influence of the United States and international financial institutions, South America opened space for economic policies and conflict‐resolution strategies that otherwise would never have been considered. Despite the value of South–South relations, this trend has attracted little scholarly attention. Yet, this study finds that this unique set of alliances played a crucial role in reestablishing relations between Colombia and Venezuela (2008–2010), resolving Argentina's financial crisis (2003–2007), and ending over 50 years of civil war in Colombia (1964–2016). Even more ambitiously, this study develops an innovative theoretical framework called post‐hegemonic regionalization. This new framework is necessary because traditional theories have not kept pace with South–South relations and thus yield little insight into South America. This study, therefore, fills an important gap in the literature. It offers compelling and rich accounts of unfamiliar yet crucial events in South American politics and addresses a theoretical deficiency.