With the present turbulent business environment, organizations are in need of organizational citizenship behavior (OCB) from employees ever before. The purpose of this study is to investigate how transformational leadership (TL) of a leader and psychological empowerment of subordinates are related to OCB of the employees apart from defined roles and responsibilities. The data were collected using self-administered anonymous questionnaire, from 130 employees of an apparel sector manufacturing organizations in Sri Lanka. The positive effect of TL on OCB of employees was significant and the mediating effect of psychological empowerment on the relationship between TL and OCB of employees was also found significant, with partial mediation being supported. The theoretical development of this paper will contribute towards understanding the effects of TL and psychological empowerment on OCB and thereby contributes to the knowledge related to those concepts. This study can help in developing practices to improve the psychological empowerment of employees and also guides leaders to focus on enhancing OCB through bringing a change in the style of leadership, to the organization.