The study investigated the factors hindering knowledge sharing practices among librarians in Nigerian federal university libraries. Methods: The study was based on post-positivism research paradigm with survey research design. The UTAUT was employed as the theoretical lens underpinning the study. All the librarians from the six federal university libraries in Southwest constituted the study population. The questionnaire and semi-structured interview were adopted for data gathering. SPSS was used to analyse the questionnaire, while the semi-structured interview was analysed through thematic content analysis. Results: The study found that majority of the respondents 80(78%) disagreed that they will not share knowledge owning to poor communication and interpersonal skills. The respondents interviewed also confirmed that trust, collaboration, reward/incentives, lack of time and fund, space and so on were identified as some factors inhibiting knowledge sharing practices among the respondents. Conclusion: The study concluded that of all the identified factors responsible for knowledge sharing practices among librarians, organisational factor received the highest ranked.