ABSTRACT Background Emotional disorders, such as anxiety and depression, are highly prevalent among adolescents, emphasizing the critical importance of developing effective preventive interventions and advancing the understanding of mechanisms inherent in these interventions. Objective To conduct secondary prediction/moderation analyses of sociodemogrphic and clinical variables regarding outcomes of a transdiagnostic, indicated preventive intervention for high-risk adolescents (PROCARE-I) and an active control condition (ACC) based on psychoeducation. Additionally, mediation analyses examined the role of resilience in improved PROCARE-I outcomes. Method Sixty-four emotionally high-risk adolescents (53% female and 47% male), aged 12 to 18 years (M = 13.69; SD = 1.56), were randomized into the PROCARE-I condition (n = 36) and the ACC (n = 28). Results There was a nonspecific prediction effect, indicating that a combination of anxious and depressive symptoms is associated with higher self-reported emotional risk following the interventions. No treatment moderation effect was found. Regarding mediation analyses, receiving a transdiagnostic preventive intervention, as opposed to an intervention based solely on psychoeducation, increased resilience levels. This rise in resilience mediated the reduction in emotional risk levels, emotional symptomatology, as well as the improvement in the quality of life reported by adolescents. Conclusions Enhancement of resilience could play a fundamental role in achieving positive outcomes following a transdiagnostic preventive intervention for emotionally high-risk adolescents.