Recognizing the vital role of employees in achieving optimal performance and sustainable competitive advantage as expected, organizations need to facilitate high support for employees, implement appropriate leadership styles, and increase affective commitment within the organization. Therefore, the objective of this study is to analyze and explore: (1) the effect of perceived organizational support (POS) on employee performance and affective commitment; (2) the effect of transformational leadership on employee performance and affective commitment; and (3) the effect of affective commitment on employee performance. The covered population in this study were all employees (including managers, supervisors, and functional staff) who worked in the stone milling companies in Central Java, Indonesia. Data obtained in this study were processed statistically employing structural equation modeling (SEM) with the SmartPLS 3 software package. Based on the data analysis results on 103 respondents, this study concluded that POS had a significant effect on affective commitment and employee performance as well as transformational leadership on affective commitment and employee performance. Furthermore, affective commitment also had a significant effect on employee performance. Thus, the results of this study, theoretically and practically, can be used by all parties concerned to improve employee performance and maintain a sustainable competitive advantage.