Background: Hairpulling (HP) is a body-focused repetitive behaviour that typically begins in early adolescence. However, most research on HP has focused on adults, with large gaps in our understanding of the phenomenology and mechanisms involved in HP in adolescence. A key empirically unexplained phenomenon in pediatric HP is the common co-occurrence of depression, and anxiety symptoms. Shame is a prevalent self-critical emotion in adults with BFRBs and a significant predictor of depression and anxiety in adolescence, and therefore may partially explain relationships between adolescent HP and depressive and anxiety symptoms. Methods: This cross-sectional, survey-based study examined HP phenomenology and the mediating role of shame in relationships between HP severity and symptoms of depression and anxiety in a community-based sample of adolescents who hair-pull. One hundred twenty-eight adolescents aged 13–18 completed measures of HP phenomenology, HP severity, shame, depression symptoms, and anxiety symptoms. Results: Phenomenological findings demonstrated a relatively high prevalence of trance HP (61.8% usually/always), trichophagia (26.6% at least sometimes), and pulling from multiple sites (80.5%). Mediational analyses revealed HP severity was significantly associated with both depression (β = 0.355, p < 0.001) and anxiety symptoms (β = 0.266, p = 0.003). Shame was a significant partial mediator in the depression relationship (indirect effect = 0.192, 95% CI [0.078, 0.308]) and full mediator in the anxiety relationship (indirect effect = 0.146, 95% CI [0.053, 0.257]). Conclusions: Our phenomenological findings highlight the need for further examination of trance HP and other HP features in youth. Our mediational results suggest that shame may play a crucial role in relationships between HP and co-occurring depression and anxiety symptomology in adolescence, underscoring the potential importance of targeting shame in improved HP interventions.