Despite expanded access to HIV treatment worldwide, poor HIV care outcomes persist among adolescent girls and young women (AGYW). This study was conducted among AGYW recruited from the HPTN 068 cohort who had sero-converted to HIV during the main trial between 2011 and 2014. The aim was to examine correlates of anti-retroviral treatment (ART) use. Log binomial regression was used to estimate the crude associations between social support, stigma, and HIV status disclosure and current ART use. Adjusted analyses were also conducted controlling for age and time since diagnosis. Seventy-nine AGYW were included in this analysis. Median age of participants was 20 (range: 17 to 24) and time since diagnosis ranged from 0.5 to 4.8 years (median = 2.1). Over 75% of AGYW (n = 60) had sought HIV care at some point, with the same number reporting previous disclosure of their sero-status. However, just 43% (n = 34) of participants were on treatment at the time of the interview. Over half of participants (n = 44; 55.7%) reported social support was available to them most or all of the time, and the median stigma score was 90 (range 80-113). Adjusted analyses found higher current ART use among those who had disclosed their status (adjusted prevalence ratio (aPR): 3.19; 95% confidence interval (CI) 1.09, 9.32; p = 0.0339) and those with lower scores on the disclosure concern sub-scale of the Berger HIV Stigma Scale (aPR: 0.88; 95% CI 0.79, 0.98; p = 0.0236). ART use among AGYW living with HIV and enrolled in HPTN 068 was low despite relatively high linkage to care during the trial. Interventions aimed at minimizing individuals' concerns about disclosure and improving onward disclosure of one's status could further improve ART utilization among AGYW living with HIV in South Africa.