Background <p>Test anxiety is a common form of situational anxiety among adolescents, which can seriously affect their academic performance and mental health. Guided by Emotion Regulation Theory and Social Support Theory, this study explores the mechanism by which mindfulness influences adolescent test anxiety, introducing music therapy and social support as chained mediators.</p> Method <p>A cross-sectional questionnaire survey was conducted among 372 adolescents from a secondary school in China. Measurement tools included the Mindfulness Scale, Music Therapy Perception Scale, Social Support Scale, and Test Anxiety Scale. Correlation analysis was performed using SPSS 26.0, and chained mediation analysis was conducted using the PROCESS macro (Model 6).</p> Results <p>The results showed that mindfulness had a significant negative effect on adolescent test anxiety (β = -0.349, <i>p</i> &lt; 0.001). Music therapy mediated the relationship between mindfulness and test anxiety, with an indirect effect of -0.074 (95% CI [-0.109, -0.042]), accounting for 12.1% of the total effect. Social support also served as an independent mediator (<i>β</i> = -0.161, 95% CI [-0.216, -0.112]), explaining 26.2% of the total effect. In addition, music therapy and social support jointly played a chained mediating role (<i>β</i> = -0.029, 95% CI [-0.049, -0.014]), accounting for 4.8% of the total effect.</p> Conclusion <p>Mindfulness can alleviate adolescent test anxiety both directly and indirectly through music therapy and social support. This study reveals the potential mechanisms of mindfulness-based interventions and provides theoretical and practical implications for school-based mental health education. Especially in resource-limited settings, promoting mindfulness training and music therapy appears to be a feasible and valuable intervention strategy.</p>