Limited evidence is available on the vulnerability of Adolescent Girls and Young Women (AGYW) to sexual risk behaviour and STI/HIV. Though there are almost no statistics available on vulnerability, related literature suggests that AGYW have low awareness about sexual risk behaviour/ transmission and the prevalence of STI/HIV, making them vulnerable. We conducted a rapid review of peer-reviewed studies addressing transmission network, prevalence, incidence awareness, common determinants of sexual risk behaviour/STI/HIV, health-seeking behaviour and existing interventions addressing the situation among AGYW (age 15–24) to inform the evidence gap in this crucial area of research. We registered the study in PROSPERO (CRD42023403713). We developed detailed inclusion/exclusion criteria, searched JSTOR, PubMed, Google Scholar, Science Direct and Population Council Knowledge Commons databases and followed the guidance from Cochrane Rapid Review to develop the rapid review. We also searched the bibliography of the included studies. We included the English language peer-reviewed quantitative, qualitative, mixed method studies published from Jan 1 2000 to Mar 31 2023. Six reviewers extracted data, and the seventh reviewer independently assessed the quality. Ninety-six studies met the inclusion criteria. We used descriptive statistics and narrative synthesis methods for data analysis. We also conducted a Risk of Bias Assessment (RoB) to check the quality of the included studies. Inadequate literature was found on the transmission network. Prevalence and awareness of STI/HIV are low among AGYW. However, Female Sex Workers, sex-trafficked women or drug users in this age group suffer more. Age, education, income, relationship dynamics with spouses/partners, multiple partners, and substance use are crucial in determining STI/HIV. Traditional sources of health seeking are more popular than formal sources because of social stigma. Mass media campaigns, community mobilization programs, and life skills training programs increase awareness about HIV, condom use and self-efficacy. The inclusion of only English language studies and not conducting meta-analysis because of high heterogeneity are some of the limitations of the study.