This study aimed to investigate the association between polyvictimization and offline and online sexual harassment and whether the association might be mediated by internalizing problems, low school satisfaction, and dropping out of school. The analytic sample was derived from the Children and Youth Rights Survey in South Korea. It consisted of 6353 adolescents responses to the sexual harassment question and a set of other questions in the middle and high school questionnaires. The findings showed a direct association between polyvictimization and offline and online sexual harassment. Adolescents who were polyvictimized were more likely to be victims of both forms of sexual harassment. Furthermore, polyvictimization was positively related to dropping out of school, which was positively associated with offline sexual harassment. The findings from the study have significant implications for future research and practice.