Academic anxiety in adolescents is linked to reduced learning participation, avoidance of evaluation, and difficulties in emotion regulation. Although school-based cognitive-behavioural therapy (CBT) has strong evidence, implementation is often limited by low early engagement and variability in delivery. This study evaluated the feasibility and change trajectory of KREATIP, an expressive music-integrated CBT protocol that uses affective musical engagement as a proposed gateway to cognitive reflection in school counseling. Using a quasi-experimental non-equivalent comparison group design with repeated measurements (pretest, posttest, and 4-week follow-up), we screened 1,707 students across four secondary schools in Sambas Regency, Indonesia, and allocated 96 eligible, matched students to KREATIP (n = 48) or routine verbal school counseling (n = 48). The KREATIP group received 6–8 sessions. Implementation fidelity was high (91%), indicating consistent delivery across schools. Linear mixed-effects models showed significant time × group interactions for academic anxiety and emotion regulation. Compared with routine counseling, participation in KREATIP was associated with greater reductions in academic anxiety and greater improvements in emotion regulation across the study period. These findings are consistent with the hypothesis that integrating structured musical activities as an emotional activation phase may support students’ psychological accessibility to CBT-oriented processes in school settings; however, this pathway was not directly measured and should be tested in future process-oriented research. Music is positioned as a facilitative entry to therapy rather than a stand-alone treatment. Mechanisms of change and causal effects require further longitudinal research.