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Background The prognostic role of cardiac MRI (CMR) parameters included in the revised Task Force Criteria (rTFC) and advanced markers such as myocardial strain in pediatric and adolescent arrhythmogenic right ventricular cardiomyopathy (ARVC) remains insufficiently defined.Methods This multicenter cohort included consecutive patients diagnosed with ARVC before age 21 who underwent CMR as part of rTFC-based diagnostic evaluation. Demographic and clinical characteristics, CMR-derived myocardial strain, and follow-up outcomes were systematically collected. Severe cardiac outcomes were defined as cardiac death, heart transplantation, and malignant ventricular arrhythmias (MVA).Results A total of 102 patients with ARVC (mean age 16 ± 3 years; 72% male) and 50 controls (mean age 16 ± 3 years; 74% male) were included. Over a median follow-up of 58 months, 51 (50%) patients experienced severe cardiac events and 28 (27.5%) patients reached MVA events. RV global longitudinal strain (RVGLS) discriminated severe events better than RV ejection fraction (AUC 0.79 vs 0.69; DeLong P<0.001). Kaplan–Meier curves demonstrated that RVGLS <12.2% identified patients at higher risk of severe cardiac events (log-rank P<0.001) and MVA events (log-rank P<0.001). In multivariable Cox analysis adjusted by clinical and imaging parameters, reduced RVGLS was independently associated with severe cardiac events (HR 1.14; P<0.001) and MVA events (adjusted HR 1.16; P=0.001). Among all rTFC items, removal of CMR criteria led to the largest decline in model discrimination (Δc = -0.264).Conclusions Pediatric and adolescent ARVC exhibits a highly malignant clinical phenotype, with CMR serving as the crucial component of rTFC evaluation. Beyond conventional RV functional parameters, measurement of RV GLS may further enhance the prognostic yield of CMR and refine risk stratification in this high-risk young population.