Social media plays an increasingly important role in school activities. The study analysised 2,122 eligibility bibliographic records from 2005 to 2021 were extracted from the Web of Science database. This study employs a bibliometric method to analyze the use of social media on K-12 education worldwide. We concerned the following issues: the annual publication of Social Media in General Education (SMGE), the main characteristics of the SMGE research community, the primary sources in the field, the leading research themes and the new research topics in the field of SMGE. The results represented an annual growth trend of 17.15%. Countries with the highest number of publications were the US, England, Australia, China, and Turkey. The research community consisted of small groups; and Valcke M from the University of Ghent (Belgium) was one of the leading authors with large number of publications and citations. Sources focused on four scopes: Language Education, Educational Technology, Teacher and Teaching Education, Science Education. Furthermore, six themes were developed: SMGE's environment, ICT integration, teachers' beliefs and teaching practice, students' learning, teachers' motivation and engagement, SMGE's learning approach. Two prominent topics were COVID-19-related, online and distance learning. The findings represent the basic information of the SMGE knowledge base considered as a source of reference for teachers, school managers, and policymakers interested in SMGE research and suggest further research directions.