Religiosity may be considered as a fundamental trait that defines Nigerians as a people. Although it is a concept that underlies all aspects of human behaviours, its impact on employees (r= -.136, p<0.01); extrinsic religiosity and organisational involvement (r= -.122, p<0.05; and a positive correlation between extrinsic religiosity and interpersonal relationship (r =.137, p<0.01). The result further revealed that intrinsic and extrinsic religiosity jointly predicted OCB ( = .050, F (2,356) = 9.303, p<.01). However, only the intrinsic religiosity dimension significantly contributed to employees' demonstration of OCB ( =.223, p<.01); extrinsic religiosity did not make significant contribution to employees' demonstration of OCB ( = -.036, p>0.05). It was concluded that the employees' intrinsic religiosity positively impact their demonstration of OCB in the workplace. Consequently, this study recommended management support of intrinsic religiosity within the purview of established work ethics.