The objective of the present study was to examine the effects of using gamification implemented in immersive virtual reality for the promotion of library services in the university library including knowledge acquisition, knowledge retention and user engagement. In terms of research procedure, we divided the participants into Gamified and Non-Gamified virtual reality groups, and both groups were asked to perform the pretest questionnaire of cognitive assessments. Then, participants were informed to use virtual reality to finish all the levels within one month in the library lab setting of the university. We performed post-tests to evaluate the knowledge acquisition, including a delayed post-test of three months to verify the knowledge retention. We also collected the user data to analyze the participant behavior. Results showed no significant differences among the Gamified and Non-Gamified groups in terms of knowledge acquisition, but showed significant difference in knowledge retention and user engagement. These findings supported the presumption that the gamified virtual reality approach can improve the library user's access and knowledge retention of library services.