This study investigated social media use for information dissemination by librarians in federal university libraries in Southwest Nigeria. A descriptive survey method was adopted for the study, while the sample consisted of all 82 librarians in the selected universities. A questionnaire was the instrument used for data collection, while the data collected was analyzed through SPSS. The study established that there was a high level of awareness of social media tools like Facebook, Google+, Twitter, LinkedIn, Academia.edu, and the other social tools found in the study, but Facebook, Google+, and Twitter were the mostly used for disseminating information. Based on the findings, conclusion and recommendations were made.