<p>Virtual Reality (VR) biofeedback (BF) may be regarded as a viable means to overcoming barriers of traditional 2D-BF. Combining fully immersive VR-BF with gamification promises to particularly benefit children and adolescents. As data on children is scarce, this multicenter RCT set out to evaluate a self-developed VR-BF game in young patients with stress related disorders. 9–18-year-olds (M_age = 13.34, SD_age = 1.99 in the overall sample) with a diagnosis of anxiety and/or mild to moderate depression were randomized to 10-session of heart rate based, fully immersive VR-BF-training (n = 19) or of standard 2D-BF-training (n = 20). Three assessments (baseline, post-training, 3-month-follow-up) were performed for chronic stress, including the two subscales helplessness and self-efficacy (primary outcome), as well as for symptom severity, the ability to relax and health related quality of life (HrQoL; all secondary). Data were analyzed using repeated measures ANOVAs. Improvements in both groups post-treatment and at 3-month-follow-up were found for chronic stress (helplessness and self-efficacy), for emotional symptoms and peer relationship problems, for the ability to relax at school/with peers, and for HrQoL psychological well-being, self-worth, peer- and school-related QoL. Yet, there were no between-group differences regarding treatment outcomes or training-evaluations, and no side effects were detected. These findings imply that VR-BF is as effective as 2D-BF. While this finding is encouraging, it also calls into question the added benefit of VR for this treatment. The design of VR-BF may need critical reevaluation, particularly with regards to reinforcing gamification elements and considering a broader range of physiological signals.</p><p> <?qj left?> <?noindent??><i>Registration of Trial</i>: OSF: osf.io/387wq; German Clinical Trial Registry: DRKS00033887 (<a href="https://drks.de/search/de/trial/DRKS00033887">https://drks.de/search/de/trial/DRKS00033887</a>).</p>