The emergency and rising of social media otherwise known as citizen media in this digital era have revolutionalised the socio- economic and particularly political development of Nigeria. It offers platform for political debates, political campaign and political mobilization especially in the 2015 General Election in Obabra Local Government of Cross Rivers state. The research, therefore, examines Social Media as Agenda Setters in the 2015 General Election in Nigeria (A case of social media usage by electorate in Obubra). Cross-sectional survey research method was adopted in which data were collected among residents in Obubra L.G using the questionnaire as a data collection instrument. Two hundred (200) copies of questionnaires were distributed, out of which, one hundred and ninety two (192) copies were retrieved and analysed. Findings show that many of the respondents participated in the 2015 election while they also search and participated in political debate and discussions on social media before, during and after the election with many served as voters during the 2015 elections. It is also established that through social media, citizens in Obubra L. G set agenda on different political matters, demonstrated high online debates and supports for political parties of interest. In the same vein, social networking usage during the election was very high for the first time in Nigeria political history, no wonder many submitted that their participation in the election was as a result of the online discussion platform such as facebook and twitters. Similarly, lots of respondents were busy reading and commenting on political matters during the 2015 electioneering period. It was recommended that social media should be improved to enhance better public mobilization, sensitization and true democracy in Nigeria through citizen sensitization programmes rather than hate words, name calling and posting of unverified information or result during election.