Abstarct: The present study aimed to examine the effect of green human resource management practices on organizational citizenship behavior for the environment, considering the mediating role of employee engagement and the moderating role of employees’ personality traits. In terms of purpose, this study is applied, and in terms of data collection method, it is a descxriptive-correlational survey. The statistical population consisted of managers, supervisors, and experts working in the main production lines of Iran Khodro Central Factory. baxsed on Morgan’s table, 357 respondents were selected as the statistical sample. Data were collected using a standardized questionnaire baxsed on a five-point Likert scale, including the constructs of green recruitment and selection, green training and development, green reward management, employee engagement, organizational citizenship behavior for the environment, and employees’ personality traits. Data analysis was conducted using SPSS and SmartPLS software, and the research model was tested through partial least squares structural equation modeling. The findings revealed that green recruitment and selection, green training and development, and green reward management had positive and significant effects on organizational citizenship behavior for the environment. Moreover, all three green HRM practices had positive and significant effects on employee engagement. The results also indicated that employee engagement had a positive and significant effect on organizational citizenship behavior for the environment. In addition, the mediation analysis confirmed that employee engagement mediated the relationships between green recruitment and selection, green training and development, and green reward management with organizational citizenship behavior for the environment. Furthermore, the moderating effects of employees’ personality traits on the relationships between the three green HRM practices and employee engagement were confirmed. The coefficient of determination showed that the model explained 52.8% of the variance in employee engagement and 57.7% of the variance in organizational citizenship behavior for the environment. baxsed on the findings, it can be concluded that the effective implementation of green human resource management practices, along with enhancing employee engagement and considering employees’ personality traits, can improve voluntary environmental behaviors in manufacturing organizations.