This study aims to explore the impact of absorptive capacity, emotion regulation, and knowledge management on performance, in Vietnam. The qualitative method is based on an overview of previous studies, the research team builds the first scale. For the quantitative research, data was collected using the convenience sampling method from a total of 536 Small and Medium Enterprises in the Mekong Delta. Owners, directors, and managers were targeted to be interviewed. The methods of exploratory factor analysis (EFA), confirmatory factor analysis (CFA), and structural equation modeling (SEM) are used to analyze the data. The findings revealed that the quality of the supervisor-employee relationship is a crucial factor in enhancing business performance. Specifically, the study found that absorptive capacity and emotion regulation have a positive influence on performance through the mediating role of knowledge management. The study suggests that enhancing absorptive capacity and emotion regulation in the enterprise and promoting the role of knowledge management can contribute to increasing business performance. This has great implications for firms looking to remain competitive in the market. By investing in these areas, firms can ensure that they are utilizing their resources effectively and efficiently to drive growth and success.