This study investigated the effect of supplier quality assurance practices on business performance, with a focus on Aramex Uganda, a leading logistics company. Supplier quality assurance, encompassing supplier selection and evaluation, supplier performance monitoring, and continuous improvement initiatives, plays a pivotal role in ensuring operational efficiency, service reliability, and customer satisfaction in logistics operations. The study aimed to assess how these practices influence the operational and financial outcomes of the organization. A descriptive cross-sectional research design was employed, using a mixed-methods approach that combined quantitative and qualitative data collection. The study population consisted of 120 employees involved in logistics operations, procurement, and supplier management, from which a sample of 92 respondents was selected using stratified random sampling and purposive sampling for managerial staff interviews. Data were collected using structured questionnaires and semistructured interviews. Quantitative data were analyzed using descriptive statistics, Pearson correlation, and multiple regression analysis, while qualitative data were analyzed thematically to provide contextual insights. The findings revealed that supplier selection and evaluation, supplier performance monitoring, and continuous improvement initiatives all have significant positive effects on business performance. Supplier performance monitoring was identified as the most influential predictor, demonstrating its critical role in enhancing operational efficiency, reducing service delays, and improving customer satisfaction. Continuous improvement initiatives were also found to strengthen supplier relationships and foster long-term competitiveness. Overall, supplier quality assurance practices collectively explained 65.6% of the variation in business performance, indicating their strategic importance to organizational success. The study concludes that effective supplier quality assurance is a critical driver of business performance in logistics companies. It is recommended that Aramex Uganda enhance supplier selection criteria, strengthen performance monitoring systems, and expand continuous improvement programs to maximize operational efficiency and customer satisfaction. The findings provide practical implications for logistics firms seeking to optimize supplier management practices and enhance competitive advantage. Additionally, the study identifies areas for future research, including the integration of digital technologies and exploration of moderating factors such as organizational culture and regulatory compliance