Purpose: The study aims to investigate the effect of autonomy on employee job performance and the mediation effect of engagement. It also explores whether an employee’s age moderates the model. Design/methodology/approach: Data were collected through a face-to-face survey administered to various types of workers in their workplaces. The selection of companies was based on a database available at the university. Response rate was 35%, yielding 210 instruments with complete responses. Structural Equation Modeling was the chosen method for data analysis. Findings: Results demonstrate a positive and significant relationship between autonomy and engagement as well as between engagement and job performance. Moreover, engagement plays a full mediating role in the relationship between autonomy and job performance. Additionally, while age does not moderate the relationship, it does have a differential impact on the mediation process. Practical implications: The creation of management strategies focused on resources such as autonomy must be adapted according to seniority, with the purpose of enhancing employee engagement and performance in today’s organizations. Originality/value: This paper closes a gap between autonomy and Job Demands-Resources theory by providing evidence on the effects of autonomy, engagement and age on job performance.