This study aims to systematically review and synthesize the effectiveness of juvenile delinquency prevention and intervention programs, with a particular focus on differences across prevention levels (primary, secondary, and tertiary). Programs were categorized by prevention level, and within each level, variables were further classified by participant age, delinquency type, and outcome factors (delinquent behaviors and delinquency-related factors). A total of 59 studies published in South Korea between 2000 and June 2025, including peer-reviewed journal articles and dissertations, were analyzed using systematic review and meta-analytic methods to estimate effect sizes. The results indicated that the overall effect size was largest in secondary prevention programs. In addition, large effects were consistently observed across all sub-variables within secondary prevention, including participant age, delinquency type, and outcome factors. For primary and tertiary prevention, significant differences in effect sizes were found depending on the variables, suggesting differential patterns of effectiveness across prevention levels. These findings highlight the importance of early identification and intervention for at-risk youth and suggest that prevention-level-specific program design may enhance intervention effectiveness. This study provides integrated evidence on the effectiveness of juvenile delinquency prevention and intervention programs and offers foundational data for future program development and policy implementation.