<p>In recent years, social media use among university students has received increased surveillance partly due to the harmful effects it had on people’s mental health during the COVID-19 pandemic. Research on this topic has identified several individual and contextual factors that may influence the relationship between social media use and internalizing symptoms (i.e., depression and anxiety). One factor that has received less attention, however, is mindfulness. Consequently, the current study examined whether mindfulness moderated the association between three dimensions of social media engagement (i.e., affective, behavioral, cognitive) and depressive and anxious symptoms. Participants were 2,737 students attending two universities in the United States. Results indicated (a) positive associations between the affective and behavioral forms of social media engagement and internalizing symptoms, (b) negative links between mindfulness and internalizing symptoms, and (c) a buffering effect of mindfulness on the relationship between affective social media engagement and depressive symptoms. This study affords valuable insights into how mindfulness can mitigate the mental health consequences of social media engagement, with practical implications for universities and social media teams aiming to support student well-being.</p>