In this article, we argue that Brazil’s ‘exporting vocation’ is not a natural tendency but the result of national political and economic projects aligned with the international context and external interests. To support this thesis, we reconstructed the trajectory of rural extension services during the 20th century in three distinct phases, according to the official philosophical and pedagogical perspectives adopted in each. Based on extensionist reports and an interdisciplinary bibliographical review, our objective is to present the sociopolitical and economic panorama along with the motivations, general characteristics, and consequences of the extension service in establishing Brazil as an agribusiness giant. We conclude that rural extension services assisted rural and agrarian development that favoured the agrarian elite in the concentration of land, resources, and knowledge. It also consolidated agribusiness as an intensely active political category at all levels of Brazilian government.