Background.Lack of relevant data has continued to militate against the development of policy and practice toward identification and treatment of alcohol/substance abuse among adolescents coming in contact with the juvenile justice system in Nigeria. This study aims to provide such data, including its policy/practice implications.Methods.One hundred and seventy eight (178) adolescents, who are representative of adolescents within the youth correctional services of Lagos jurisdiction, were interviewed using the alcohol and substance abuse section of the Kiddies’ Schedule for Affective Disorders and Schizophrenia.Results.The lifetime prevalence rate of abuse of/dependence on any of alcohol or other substances was 22.5% (alcohol, 12.3%; illicit substance, 17.9%). Males were overrepresented among those with any substance use disorder, with gendered prevalence rate as high as 35%. Having had a lived-experience of being a street-child was the single most significant independent factor (Odds ratio (OR), 8.4; p = 0.007) associated with lifetime alcohol substance use disorder.Conclusions.Substance use disorder is highly prevalent among adolescents within the juvenile justice systems in Lagos Nigeria. There is need for deliberate incorporation of alcohol and substance abuse screening and intervention as part of individual care plan in youth correctional facilities in Nigeria. Practical steps toward achieving this were drawn from local reality and international best practices.