Background <p>Fear of Missing Out (FoMO) and Peer Pressure are intertwined among university students and are highly associated with Social Media Addiction. This study explores the potential moderating role of Self-Authenticity in the associations among peer pressure, social media-related factors, and FoMO.</p> Methods <p>A cross-sectional survey was administered to 397 Chinese university students. Five variables were measured: Self-Authenticity, Peer Pressure, Social Media Addiction, Online Social Comparison, and FoMO. Structural equation modeling (SEM) and moderation analyses were utilized to examine the structural relationships among these variables.</p> Results <p>Social Media Addiction and Online Social Comparison exhibited indirect association patterns between Peer Pressure and FoMO. Self-Authenticity demonstrated significant negative predictive effects on all variables in the model. Additionally, Self-Authenticity negatively moderated the association between Peer Pressure and FoMO (where the direct predictive path became non-significant after its inclusion), while demonstrating positive moderating effects on the associations from Peer Pressure to Social Media Addiction, and from Social Media Addiction to Online Social Comparison.</p> Conclusion <p>Self-Authenticity is negatively associated with baseline levels of peer pressure, social media-related risks, and FoMO. Grounded in the S-O-R framework, the study highlights Self-Authenticity as a key individual-level variable that moderates the statistical associations among external pressures, digital behaviors, and psychological states. Given the cross-sectional design, these findings represent structural associations rather than causal mechanisms.</p>