Functional illiteracy continues to constrain students’ academic and long-term opportunities in the Philippines. One factor that heightens this risk is bullying, which undermines both psychosocial well-being and academic achievement. This study used 2022 Programme for International Student Assessment (PISA) data to examine whether school belonging mediates the effect of bullying on reading literacy, and whether family support moderates these pathways. A moderated mediation model across ten plausible values, controlling for socioeconomic status, gender, and school risk, showed that bullying was negatively associated with reading literacy, partly through reduced belonging. The negative impact of bullying on belonging was stronger when family support was higher, but family support did not moderate the belonging–literacy link. These findings suggest that while families can buffer psychosocial harm, their role in mitigating bullying’s academic consequences is more complex and context dependent.