Agribusiness, including all its dimensions, is the largest economic sector in Brazil and plays a fundamental role in the development of the country's economy. About one-fourth of the Brazilian Gross Domestic Product (GDP) is composed of agribusiness. The objective of this article is to evaluate the participation of agribusiness in the economy of an important region of Brazil from 2010 to 2015. The evaluation was carried out through the decomposition of GDP, with an analysis of aggregate inputs, agro-livestock products, industrialization, and services. This article presents three main contributions to the understanding and composition of agribusiness GDP. The novelty of this article lies in the fact that it is the first work in the literature to present the steps of the methodology for calculating GDP in a region representing Brazilian agribusiness, considering its aggregates and relating the generation of taxes and other factors. In addition to the empirical and methodological contributions, this article highlights the relevance of agribusiness to the Brazilian economy, which, in turn, has relevance to global agribusiness.