BACKGROUND: Chronic non-communicable disease comorbidities are a major problem faced by people living with HIV (PLHIV). Obesity is an important factor contributing to such comorbidities and PLHIV face an elevated risk of obesity. However, there is data paucity on the intersection of obesity and HIV in adolescents and youth living with HIV (AYLHIV) in sub-Saharan Africa. We therefore aimed to investigate the prevalence of abdominal obesity and associated multilevel factors in AYLHIV in peri-urban Cape Town, South Africa. METHODS: We conducted a cross-sectional study enrolling AYLHIV aged 15-24 years attending primary healthcare facilities in peri-urban Cape Town in 2019. All measures, except for physical examination measures, were obtained via self-report using a self-administered electronic form. Our outcome of interest was abdominal obesity (waist-to-height ratio ≥ 0.5). We collected individual-level data and data on community, built and food environment factors. Data was summarized using descriptive statistics, stratified by obesity status. Multilevel logistic regression was conducted to investigate factors associated with abdominal obesity, adjusted for sex and age. FINDINGS: A total of 87 participants were interviewed, 76% were female and the median age was 20.7 (IQR 18.9-23.0) years. More than two fifths had abdominal obesity (41%; 95% CI: 31.0-51.7%), compared to published rates for young people in the general population (13.7-22.1%). In multilevel models, skipping breakfast (aOR = 5.42; 95% CI: 1.32-22.25) was associated with higher odds of abdominal obesity, while daily wholegrain consumption (aOR = 0.20; 95% CI: 0.05-0.71) and weekly physical activity (aOR = 0.24; 95% CI: 0.06-0.92) were associated with lower odds of abdominal obesity. Higher anticipated stigma was associated with reduced odds of obesity (aOR = 0.58; 95% CI: 0.33-1.00). Land-use mix diversity (aOR = 0.52; 95% CI: 0.27-0.97), access to recreational places (aOR = 0.37; 95% CI: 0.18-0.74), higher perceived pedestrian and traffic safety (aOR = 0.20; 95% CI: 0.05-0.80) and having a non-fast-food restaurant within walking distance (aOR = 0.30; 95% CI: 0.10-0.93) were associated with reduced odds of abdominal obesity. The main limitations of the study were low statistical power and possible reporting bias from self-report measures. CONCLUSIONS: Our findings demonstrate a high prevalence of abdominal obesity and highlight multilevel correlates of obesity in AYLHIV in South Africa. An intersectoral approach to obesity prevention, intervening at multiple levels is necessary to intervene at this critical life stage.