The study examined social media as tools for political participation and mobilization in Osun West Senatorial Bye-Election in 2017. The emergence and proliferation of social media otherwise known as citizen media have reshaped political education and mobilization in Nigeria. It offers a platform for political debates, cyber activism, political campaign, political communication, and political mobilization. The survey research method was used with the questionnaire serving as the research instrument to gather the required data. Findings in the study show that majority of the respondents used social media to contribute to debates, sharing opinions and getting updates during the re-run election while it is also evidence that majority of the respondents use Facebook, Twitter, Instagram, and Whatsapp more than any other social during the period. It is recommended that social media be used to enhance and improve public communication, mobilization, sensitization and true democracy in Nigeria particularly during voters’ registration, campaign and voting processes.