Purpose-Drawing on trait activation theory, this study proposes an integrated moderated mediation model that examines the interaction between proactive personality and perceived support as antecedents of person-environment fit and work attitudes. Design/methodology/approach-Data were collected in a field study from 153 full-time employees recruited through Qualtrics labs. Findings-Proactive employees strive to improve person-environment fit, which in turn leads to higher job satisfaction and stronger intentions to remain within their organization. This indirect relationship is further strengthened when proactive employees perceive high levels of support from various sources within their work environment, including the organization, workgroup, and supervisors. Originality/value-This study highlights the important interplay between proactive personality and perceived support in shaping person-environment fit and fostering positive work attitudes, offering deeper insight into how and when proactive personality influences job satisfaction and retention. Practical implications-Given the substantial costs associated with employee dissatisfaction and turnover, taking into account proactive personality in hiring decisions, combined with providing work-related support after hiring, can result in favorable employee outcomes.