<p>The problematic use of social media has emerged as a significant challenge confronting contemporary college student populations, raising concerns about its harm to psychological well-being. Although prior studies explored how social support and resilience can reduce addictive behaviors, few have examined how these two factors jointly link social media addiction and mental health issues, or how gender shapes these links. This study addresses these gaps by proposing a moderated chain mediation model based on stress-buffering and resilience theories. A total of 1,020 Chinese undergraduates took part. Standardized tools assessed mental health issues, social support, resilience, and social media addiction. PLS-SEM was used to analyze mediating and moderating pathways. Analysis revealed a significant positive relationship between social media addiction and mental health issues after controlling for covariates. A sequential mediation analysis revealed that this association was mediated by social support and resilience. Moreover, gender was found to moderate the links from social media addiction and social support to mental health issues, with stronger effects seen in female students. However, gender did not significantly moderate the relationship linking resilience to mental health issues. This study provides an initial examination of how social support and resilience serve as chain mediators between social media addiction and mental health issues, and highlights gender’s moderating role. The findings inform targeted interventions and resilience programs for students.</p>