Social media’s potential for knowledge dissemination is under-utilized due to limited user participation. This study systematically reviews factors affecting knowledge-sharing intentions on social platforms using the ROSES protocol. We searched Scopus and Web of Science for quality, relevance, and rigor, finding that 65% of the articles shared were published in high-quality journals (Q1 or Q2), with the Journal of Knowledge Management accounting for 15%. Since 2015, 62.5% of research has been published, highlighting increased activity. Quantitative methods dominated (95%), with Zhihu being the most studied platform. We identified four key themes—psychological, technological, environmental, and social—covering 47 determinants centered on trust and attitude, primarily based on individual and social behavior theories. This is the first systematic exploration of elements influencing knowledge-sharing intentions on social media, providing insights to enhance user interaction and guide social media strategies in knowledge-centric organizations.