<p>The transition to the systems of the circular economy is becoming a crucial quality for organisations that aim to improve their sustainability performance under increasing environmental pressure. However, a successful circular transformation involves not only technology and operations, but also organisational practices that promote environmentally responsible behaviour among all employees. Despite the growing interest of scholars in circular economy and sustainability, the existing body connotes system-level solutions and supply-chain solutions more, indicating a gap in the empirical research that elucidates the human and behavioral processes that make sustainability happen particularly in emergent economies. The gap in this study is that sustainability-oriented human resource practices influence organizational sustainability performance in terms of employee behavior, and that circular economy practices can strengthen the impact of the former. Based on survey data of employees in the textile manufacturing industry of Pakistan, the proposed study takes a quantitative research design and uses the partial least squares structural equation modelling to test the hypothesized relationships using SmartPLS4. This model measures the directs impact of the sustainable HR practices on sustainability performance, the mediating effect of the pro-environmental employee behavior, and the moderating effect of the circular economy practices. The results indicate that sustainable HR practices play a major role in enhancing pro-environmental behavior among the employees, which subsequently enhances sustainability performance. Also, circular economic practices increase the connection between employee behavior and sustainability performance. The study contributes to the literature on the circular economy and sustainability by connecting the HR practices and employee behavior, offers new empirical evidence in a developing-economy setting, and gives valuable advice on how firms can engage in sustainable transformation.</p>