Although servant leadership is recognized as a significant predictor of workplace well-being, research exploring the underlying mediating and moderating mechanisms that define this link is limited. To bridge this gap, the current study draws on the Job Demands-Resources theory to propose a theoretical hypothesis model, incorporating job autonomy as a mediator and proactive personality as a moderator. By collecting 817 valid questionnaire responses from 28 secondary schools in China, the current study employed hierarchical regression analysis, structural equation modeling, and bootstrapping techniques to test the proposed model. The findings indicate that job autonomy partially mediates the positive link between servant leadership and workplace well-being, while proactive personality enhances the positive link between servant leadership and job autonomy. These insights not only deepens our understanding of the mechanisms through which servant leadership influences workplace well-being but also provides substantial evidence of the role that proactive personality plays in amplifying the effectiveness of servant leadership. In light of the findings from the current study, secondary schools should cultivate a servant leadership style among administrators to achieve the strategic goal of enhancing teachers' workplace well-being.