This study examined the librarians’ internal job rotation and mentoring as a correlate of job performance in university libraries in the South-South. Nigeria Two research questions guided this study and two hypotheses were tested at 0.115 level of significance. The population of the study was 108 librarians. Two sets of questionnaires titled Librarians Internal Job Rotation and Mentoring Questionnaire (LURMQ) and Job Performance Questionnaire (JPQ) were the instruments used for data collection. The reliability of the instrument was established using the Cronbach Alpha method to measure librarians' internal job rotation and mentoring to the coefficient of 0.835 and 0.741 while instrument for job performance resulted in 0.669. The data collected for the study were analyzed using Pearson Product Moment Correlation (r) method to answer research questions while t-test analysis was used to test the null hypotheses. The findings of the study revealed that there is a positive and strong relationship between librarians' internal job rotation and job performance in university libraries and a significant relationship between librarians' internal job rotation and job performance in university libraries in South-South Nigeria. There is a positive and strong relationship between librarian mentoring and job performance in university libraries and a significant relationship between librarians mentoring and job performance in university libraries in the South-South, Nigeria, Based on the findings, the study recommended among others that University library management should develop a developmental programmes policies, procedures and guidelines that will encourage librarians perform and actualize the goals of the library institution establishing it. There should be a workable written statement of aim to guide and sustain internal job rotation and mentoring programmes.