Librarians’ professional development is the process of constantly strengthening professional attainment, broadening academic knowledge, enhancing the professional skills, and improving library services. The new Massive Open Online Courses necessitate academic librarians to be lifelong learners who can take advantage of available opportunities to improve their professional competence continuously. However, much research has not been done on perception of academic librarians to the use of MOOC as professional development tools. Therefore, this study examined perception of academic librarians to the use of MOOC as professional development tools in selected university libraries in Osun State, Nigeria. Also, the study adopted the descriptive survey design. Questionnaire was the instrument used for data collection and descriptive statistics were used for data analysis. Three Nigerian universities were selected which has a total number of Thirty eight (38) academic librarians. The total enumeration sampling technique was used to study all respondents for the study. The findings showed that academic librarians are fully aware of massive open online course as a tool for professional development in University libraries in Nigeria.