Adolescence, characterized by both remarkable brain plasticity and vulnerability to psychiatric disorders; represents a uniquely propitious time window for targeted early interventions. Mindfulness-based interventions (MBI) have garnered increasing interest as cost-efficient, non-invasive and non-pharmacological approaches to enhancing mental health. While solid evidence supports the mental health benefits of MBI in adults, results in adolescents remain mixed. In particular, there is contradictory evidence regarding the use of MBI for healthy adolescents, underscoring the need for further research on its underlying mechanisms. One emerging mechanism mediating the beneficial effects of MBI is improved emotion regulation. Indeed, impaired emotion regulation is increasingly recognized as an early and transdiagnostic marker for psychiatric disorders. Therefore, we aimed to examine the impact of MBI on emotion regulation (ER) strategy use in healthy young adolescents. This study is a two-arm, wait-list, randomized controlled trial (RCT) of an 8-week MBI involving 70 adolescents from a non-clinical sample, aged 13 to 15. This study reports secondary outcomes on the impact of the MBI on emotion regulation strategy (ERS) use during a naturalistic task of emotion reactivity and regulation. Post-hoc t -tests on a multilevel logistic regression model (GLMM) revealed a significant decrease in the use of acceptance and problem solving, and a highly significant increase in the use of relaxation in adolescents' emotion regulation strategies after the MBI, compared to the wait-list controls. Despite the limited sample size, these secondary results of the study point to the effectiveness of MBI in improving emotion regulation strategies in adolescents from the general population, paving the way to future wider-scale research into specific mechanisms of action and into the clinical relevance of MBI in adolescents. Shedding light on these points is pivotal for validating MBI as a potential early intervention aimed at improving mental health and reducing the risk of psychiatric disorders in adolescents.