The main purpose of this study is to examine the relationship between leadership style and job commitment of library personnel in private universities in the Southwest, Nigeria. The research instrument used in the collection of data was questionnaire. In measuring the research questions and testing hypotheses, mean and standard deviation, analysis of variance (one way), correlation and multiple regression analysis and multiple pair wise comparison were used. The result of the study shows that Leadership Style had a significant relationship with the job commitment of respondents (β=.102, P>.05). Moreover, the study found out that there was significant difference in the comparative Job Commitment of Library Personnel of University (F (14,155, P <.05). Based on the findings, it was concluded that library managers should evolve leadership styles that will motivate the job commitment of their subordinates. It was also concluded that the respondents are committed to their job but the degree of commitment varies from one university to the other. The study recommends that the management can improve working conditions of the library personnel, especially the availability of material, human and financial resources so as to enhance their job commitment.