This study investigates the decision-making process that led to the inclusion of “cyberbullying” within the definition of school violence in the School Violence Prevention Act and the establishment of a definition for cyberbullying. To identify the main factors influencing this decision, the study uses Kingdon’s multiple streams framework analyzing the problem stream, policy stream, and political stream, as well as identifying the policy entrepreneurs involved. The results of this analysis are as follows. The process of establishing the policy agenda was influenced by the convergence of the political stream and the problem stream, which then combined with the policy stream. The decisive factor affecting this process was the COVID-19 pandemic, whose adverse effects on online learning and the results of school violence surveys served as critical elements within the problem stream. This stream combined with the political stream, with key factors being the side effects of online learning caused by the COVID-19 pandemic and The Blue Tree Foundation’s efforts to prevent and eradicate cyberbullying. As leading policy entrepreneurs, The Blue Tree Foundation, the Ministry of Education, and members of the National Assembly actively led the policy stream, serving as important factors in the policy decision-making process. These various factors led to the inclusion of cyberbullying in the Act on the Prevention of School Violence and the establishment of its definition.