Socioeconomic inequality is a persistent societal problem affecting various aspects of adolescent development. Existing studies have revealed that low socioeconomic status (SES) is associated with a higher prevalence of internalizing symptoms. However, little is known about the underlying factors that may mediate this relationship. The current study conducted path analyses to examine the role of academic performance and cyberbullying victimization as mediators of the association between family SES and internalizing symptoms (depressive symptoms and suicidal ideation). The sample consisted of 7333 middle and high school students (age 12 to 19 years) (50.8% female) participating in the Korean Children and Youth Rights Study. Findings indicated that SES was directly and negatively associated with depressive symptoms and suicidal ideation. There were indirect associations between SES and internalizing symptoms through academic performance and cyberbullying victimization. The findings suggest low family SES is significantly related to adolescents' internalizing symptoms, and academic performance and cyberbullying victimization are key mediators of the negative association between family SES and internalizing symptoms. Further longitudinal studies exploring the roles of family SES, academic performance, and cyberbullying victimization are suggested.