Complete dataset.

Despite the recognized need to address the prevention of sexual violence against adolescents in Nigeria, significant research gaps persist in understanding the patterns, determinants, and impacts of such violence, particularly regarding regional variations and the specific developmental needs of adolescents across different stages. This study provides Nigerian regional prevalence estimates disaggregated by gender, rural/urban, and in/out-of-school populations, while also identifying socio-demographic and cultural determinants related to increased vulnerability. A cross-sectional survey was conducted in South-West Nigeria with a sample of 961 adolescents, targeting in- and out-of-school adolescents aged 13–17 years. Descriptive statistics and logistic regression analyses were performed.The prevalence of any form of SV since age 12 was 69.4%, with higher rates among out-of-school adolescents and boys. Non-contact abuse (63.2%), passive contact abuse (41.9%), and active contact abuse (28.7%) were the most common forms reported. Peers were the dominant perpetrators (77.1%), followed by other adults (27.9%). Being male (OR 2.033), older (OR 1.214 per year), involved in a romantic relationship (OR 2.731), and experiencing SV before age 12 (OR 4.622) were significant risk factors. Higher household wealth (OR 0.902 per asset) and emotional support from both parents (OR 0.413) were protective factors.This study highlights the high burden of SV against adolescents in Nigeria, with concerning patterns of male victimization and peer perpetration. The findings emphasize the need for comprehensive, evidence-based strategies addressing emotional support, social norms, power dynamics, and economic vulnerabilities to prevent and respond to this problem effectively.