<p>Given the dearth of research on Internal Marketing (IM) in the public sector, especially in developing countries, this study investigates the relationship between IM, job satisfaction (JS), task performance (TP), and contextual performance (CP), and the mediating role of JS in this interaction among Jordanian public sector employees, focusing on governmental public sector institutions in Amman, the capital of Jordan, where a simple random sample of 373 managers was surveyed. PLS-SEM was used to verify the proposed relationships using SmartPLS 4.0 software. The results show that IM has a direct relationship with JS and TP but not with CP, contradicting the assumption that IM directly affects all aspects of employee performance. The results further confirm that JS was significantly associated with both TP and CP. Crucially, JS fully mediated the relationship between IM and CP and partially mediated the relationship between IM and TP. Finally, JS’s relationship with CP was stronger than its relationship with TP, suggesting that IM policies are more effective in enhancing employees’ voluntary extra-role behaviours. This study expands our understanding of IM within the public sector, showing that IM improves performance (TP and CP) primarily via JS. The finding that JS’s relationship with CP was stronger than its relationship with TP suggests that IM policies are highly effective in enhancing employees’ voluntary extra-role behaviours, making investment in employee-centric policies crucial for improving overall service delivery.</p>