INTRODUCTION: Child sexual abuse (CSA) is a widespread global health concern with lasting impacts. CSA is multifactorial and layered, and interventions to tackle CSA require an analysis of the key contributing factors. The main objective of this study was to explore global prevalence estimates of CSA and key contributing factors. METHODS: We systematically searched PubMed, Scopus and Web of Science for studies reporting lifetime prevalence of contact (eg, inappropriate touching or sexual acts) and non-contact (eg, exposure to sexual content or ill-intended conversations) CSA. Of 5493 articles screened, 332 met inclusion criteria. Prevalence data were stratified by population, region and abuse type. Risk factors were synthesised thematically using a socioecological framework. RESULTS: Median prevalence of reported non-contact CSA was 57.0% (range: 31.1%-80.0%). Contact CSA prevalence was higher among females (median: 14.9%, range: 2.2%-40.2%) than males (median: 6.0%, range: 0.6%-21.2%). Regional variations were notable, with sub-Saharan Africa reporting the highest contact CSA prevalence (median: 25.5%) and Latin America and the Caribbean the lowest (median: 8.5%). Vulnerable groups, including Indigenous children (median: 39.2%), orphans (37.9%) and the incarcerated (31.1%), faced higher risk. Risk factors spanned individual (shame, stigma), familial (poor supervision, dysfunction), institutional (lack of safeguards) and societal (weak legal frameworks, normalisation of abuse) levels. CONCLUSIONS: Prevalence of CSA was globally high, with 14 in 100 females reporting having experienced CSA. Multilevel interventions, particularly strengthening family supervision and institutional safeguarding, legal accountability and community awareness, are critical for the prevention of CSA.