Background: Perinatally acquired HIV may lead to worse health outcomes compared to later acquisition. We compared the demographic and clinical characteristics of youth diagnosed with HIV in childhood and adulthood, as a proxy for acquisition route (perinatal vs horizontal). Setting: Youth aged 18-24 years in 3 provinces in Zimbabwe Methods: In a representative population-based survey, participants were asked their HIV status, date of HIV diagnosis if positive, and whether they were diagnosed in childhood. A dried blood spot was taken to measure viral load. Multilevel mixed-effects generalized linear modelling was used to estimate the association between HIV acquisition time and viral non-suppression (≥1000 copies/ml). Results: 17,682 participants (60.8% female) were enrolled, 17553 (99.3%) gave a DBS sample, 1200 (6.8%) tested HIV antibody positive (7 indeterminate results) and 26 reported being HIV positive without confirmation. Of the 1226 participants living with HIV, 435 (35.5%) self-reported they were HIV-positive, of whom 196 (45.1%) were diagnosed in childhood (median age 7 years). A higher proportion of adult-diagnosed than child-diagnosed participants were female (91.2% vs 76.5%), had ever had sex (93.3% vs 61.5%), been married/cohabiting (59.4% vs 19.4%) and been pregnant (78.9% of women vs 40.0%). A lower proportion had viral suppression (39.3% vs 52.5%). Adjusting for sex, age, marital status and education, those diagnosed as children had higher odds of viral non-suppression (adjusted odds ratio=1.83, 95%CI 1.17-2.85, p=0.008). Conclusion: Youth who acquired HIV perinatally have differentiated care needs and greater risk of viral non-suppression compared to those who acquired HIV later.