Gambling among children and young people (CYP) has been associated with a range of adverse outcomes, including financial consequences, psychological distress, social difficulties, and increased risk of experiencing gambling-related harms in adulthood. Given the growing accessibility of gambling activities through digitally- enabled experiences and the expanding regulatory concerns, there is a pressing need for evidence-based interventions to mitigate harm in this vulnerable population. Despite numerous interventions aimed at reducing gambling-related harm among CYP, systematic analysis of their effectiveness remains limited. To address this gap, we conducted a comprehensive scoping review of literature published between 2008 and 2025, using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) extension for scoping reviews and the Arksey and O'Malley five-stage protocol. The PAGER Framework was employed to critique the literature. We searched eight electronic databases, supplemented by manual reference checks, for peer-reviewed studies on interventions to prevent or reduce gambling-related harm in CYP up to age 25. Of 11,972 articles identified, 40 met the inclusion criteria. Our analysis revealed four key themes: effective interventions often integrate multiple methods and actively engage participants, are theory-driven and delivered by trained practitioners, are tailored to developmental needs, and incorporate digital technologies. Common issues across studies included the absence of follow-up assessments and the use of adult questionnaires with CYP. We recommend addressing the social context and environment rather than focusing solely on individual behaviour, involving CYP in intervention development, evaluating long-term effects, and considering underserved populations such as CYP with special educational needs. This review underscores the urgent need for rigorously evaluated, evidence-based interventions to reduce gambling-related harm in CYP across educational, healthcare, and youth work settings.