This study examines the influence of the tertius iungens orientation on knowledge-sharing activities and individual job performance within enterprise social media environments. The empirical analysis reveals that knowledge self-efficacy, social interaction ties, and the norm of reciprocity positively influence the tertius iungens orientation and knowledge-sharing activities in social media, while enjoyment of helping does not have a significant influence. In addition, the tertius iungens orientation has a significant impact on knowledge-sharing activities in social media, which in turn influences individual job performance. Based on the results of this analysis, this study discusses the research findings and proposes theoretical and practical implications of the study as well as the research's limitations.