All companies in agribusiness supply chains need to be aware of the best use of available resources, which demands an integrated assessment of environmental, economic and social aspects, i.e., the Triple Bottom Line (TBL). Such analysis allows us to get a more balanced and complete understanding of the real performance of companies, supply chains and industries. Companies in the upstream of agribusinesses supply chains present some limitations, but can contribute significantly to the overall sustainability of the entire value chain. The objective of this research was to understand the role of the drivers of sustainability in dairy farming from a TBL perspective, such as assistance to producers and the value chain, and the use of better technology and management practices. A sample of 54 rural farms in the dairy supply chain of the western region of Santa Catarina, Brazil, was used to test four hypotheses about what can drive sustainability. Furthermore, first- and second-order structural equation models using SMART PLS software were used for the analysis of the data. The results obtained show that social sustainability is positively influenced by the use of good management practices, and the latter, as well as public policies, positively influence economic sustainability. Furthermore, it was found that improvements in production techniques positively influence environmental sustainability, and this is mostly influenced by the use of good management practices, and less so by policies directed at the supply chain. Finally, from the analysis of the second-order variable for sustainability, it was highlighted that the economic dimension prevails in the eyes of the farmers, as the main dimension of sustainability, and that environmental aspects are still neglected.