Questions have been raised about how social media may be experienced by adolescents with mental health concerns. Among socially anxious adolescents, social media may be experienced both negatively, because it can exacerbate core fears (e.g., negative evaluation), and positively, because it can alleviate other core fears (e.g., in-person interactions). We examined whether adolescent social anxiety is associated with social media experiences and is influenced by sex (girl/boy). Participants were 282 early adolescents (Mage = 11.79 years, 63% girls; 47% Hispanic/Latino) presenting for social anxiety evaluation and/or treatment, who completed self-report measures of social anxiety and social media experiences. Regression analyses revealed significant associations between social anxiety and both positive and negative social media experiences. We also found that social anxiety was associated with negative social media experiences for girls but not boys. The findings’ advancement of theory, research, and clinical understanding of social media use among socially anxious adolescents are discussed.