The primary art markets of Spain and Portugal developed in parallel with the dominant centers of the global art system and were shaped by delayed modernization, limited institutional support, and enduring historical and linguistic ties with Latin America. This study examines the evolution of the Spanish and Portuguese primary art markets from the mid-20^th century to the present, analyzing how geopolitical shifts and historical ties have shaped their role as mediators between Europe and Latin America. Combining a historical perspective with art market studies, the study employs a qualitative and quantitative methodology based on archival research, exhibition catalogs, and case studies of galleries and collectors. The study argues that Spain and Portugal, despite their small scale and delayed modernization, have leveraged their transatlantic connections, linguistic affinities, and private initiatives to establish resilient and internationally connected art ecosystems. Through analysis of pioneering galleries, such as Galería Luis Adelantado, Galería Travesía Cuatro, Galeria Askanasy, and Galeria Graça Brandão, and collectors including Luiz Augusto Teixeira de Freitas and Ella Fontanals-Cisneros, the analysis highlights how private actors compensated for institutional fragility and became central agents of cultural diplomacy. Events such as ARCOmadrid and ARCOlisboa further reinforced the Iberian Peninsula’s role in southwestern Europe as a platform for South–South exchanges and decolonial dialogues within the European art market. The findings demonstrate that the Iberian markets operate as transatlantic nodes that contribute to the diversification of international artistic production. By mobilizing historical affinities and cultural collaborations, Spain and Portugal have transformed their semi-peripheral condition into a strategic advantage, promoting alternative routes of art circulation and expanding the geography and narratives of the international art system.