Internet usage has become an inevitable part of daily life. Adolescents who are developmentally vulnerable due to family dynamics or who suffer psychological distress are at greater risk of problematic Internet use. This study aims to reveal the intricate psychological pathways linking family social support to problematic Internet use among adolescents and the mediating roles of hostility and depression. The study uses serial mediation analyses and Hayes PROCESS macro to examine a large sample of 2,047 adolescents (1,182 females and 865 males). Results revealed a significant negative association between family social support and problematic Internet use. Both hostility and depression were found to be critical mediators, functioning independently and sequentially in the relationship between family social support and problematic Internet use. The findings highlight the protective role of family social support against problematic Internet use among adolescents by reducing hostility and depressive symptoms. This investigation contributes to the extant literature by elucidating the psychological mechanisms underlying problematic Internet use. It suggests that interventions targeting family support systems, feelings of hostility, and depression may effectively mitigate problematic Internet use among adolescent populations.