Organizational Citizenship Behavior (OCB) is defined as an employee's voluntary behavior which is not formally rewarded in spite of its potential to increase the effectiveness and efficiency of the organization. This study aimed to investigate the mediating effect of psychological empowerment in the relationship between perception of workload and OCB. This study used the approach-avoidance motivation as the theoretical framework. Research data were collected using the snowball sampling method that was implemented in an online survey that targeted employees of various private organizations in Indonesia (N = 201). The measures used in this study were the 9-item workload subscale of the Job Demand-Resource Scale, 12-item Psychological Empowerment Questionnaire (PEQ), and 14-item OCB subscale of the Task Performance Scale. Data were analyzed using the simple mediation regression technique of Macro PROCESS developed by Hayes for SPSS software. The results of this study showed that perceived workload has a positive effect on psychological empowerment and psychological empowerment has a positive effect on OCB. Further, results showed that psychological empowerment mediates the relationship between perceived workload and OCB.