Background: Risky sexual behaviours amongst adolescents are associated with detrimental impact on their personal growth, influenced by psychosocial factors including subjective cultural norms. This systematic review aimed to examine the evidence on ASEAN countries’ adolescents risky sexual behaviour defined as sexual deviance with its associated psychosocial factors.Methods: A systematic literature review was guided by PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) for a search through four electronic databases for articles published within the time frame of 2010 and 2020 resulting in 20 articles that meet the inclusion criteria. Results: Adolescent sexual deviance in ASEAN is associated with salient psychosocial factors such as cultural norm, self-esteem, parental support/monitoring, substance abuse (alcohol/drugs/smoking), spirituality and religion. Intention, attitude and motivation of sexual transgression appear to be recurrent factors as well. Most studies are cross-sectional and quantitatively designed. The diverse and nuanced psychosocial factors of sexually deviant behaviour affirm the sexual dimension and values of absolutism, hedonism and relativism.Conclusions: Strategies for reducing risky sexual behaviours among ASEAN adolescents should take regard of subjective culture norms and psychosocial needs to achieve the goal of progress as per the ASEAN Youth Development Index. More qualitative and longitudinal approaches in future research are also recommended for more in-depth insights for appropriate intervention or rehabilitative measures.