Fuel availability is essential in supporting the sustainable economic growth of a country. The manufacturing industry, transportation activities, and shipping products between regions are the primary sectors that require a sustainable fuel supply. The fuel station contributes to distributing and delivering fuel in serving the demand for the fuel. This study investigates supplier competency's role in supporting fuel station business performance through supplier integration, vendor-managed inventory, and supply chain collaboration. The research surveyed 71 fuel stations in Timor Leste using a questionnaire designed with a five-point Likert scale. The questionnaires are distributed to supervisors or higher positions at fuel stations by distributing questionnaires by direct delivery and also through Google Forms for areas far away in downtown Timor Leste. Data from respondents were analyzed using smartPLS software version 4.0. The results found that supplier competency positively impacts supplier integration, vendor-managed inventory, and supply chain collaboration. Moreover, supplier integration positively impacts vendor-managed inventory, supply chain collaboration, and business performance. Vendor-managed inventory fuel station sites can have an impact on improving supply chain collaboration and business performance. In addition, supply chain collaboration between vendors and fuel stations in Timor Leste enables continuous business performance improvement. This research paves the way for supervisors, managers, and fuel station top management to collaborate with suppliers in maintaining inventory levels and forecasting the supply and demand for fuel procurement requirements. Finally, this research contributes to the theory of inventory optimization and supply chain performance.