Background: Perinatally acquired HIV may lead to worse health outcomes than 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 were included. 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 nonsuppression (≥1000 copies/mL). Results: A total of 17,682 participants (60.8% female) were enrolled, 17,553 (99.3%) gave a dried blood spot 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 that 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%), had been married/cohabiting (59.4% vs. 19.4%), and had 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 in childhood had higher odds of viral nonsuppression (adjusted odds ratio = 1.83, 95% confidence interval: 1.17 to 2.85, P = 0.008). Conclusions: Youth who acquired HIV perinatally have differentiated care needs and greater risk of viral nonsuppression compared with those who acquired HIV later.