INTRODUCTION: Adolescent girls and young women (AGYW) living with HIV experience poor HIV outcomes and high rates of unintended pregnancy. Little is known about which healthcare provisions can optimize their HIV-related outcomes, particularly among AGYW mothers. METHODS: Eligible 12- to 24-year-old AGYW living with HIV from 61 health facilities in a South African district completed a survey in 2018-2019 (90% recruited). Analysing surveys and medical records from n = 774 participants, we investigated associations of multiple HIV-related outcomes (past-week adherence, consistent clinic attendance, uninterrupted treatment, no tuberculosis [TB] and viral suppression) with seven healthcare provisions: no antiretroviral therapy (ART) stockouts, kind and respectful providers, support groups, short travel time, short waiting time, confidentiality, and safe and affordable facilities. Further, we compared HIV-related outcomes and healthcare provisions between mothers (n = 336) and nulliparous participants (n = 438). Analyses used multivariable regression models, accounting for multiple outcomes. RESULTS: HIV-related outcomes were poor, especially among mothers. In multivariable analyses, two healthcare provisions were "accelerators," associated with multiple improved outcomes, with similar results among mothers. Safe and affordable facilities, and kind and respectful staff were associated with higher predicted probabilities of HIV-related outcomes (p<0.001): past-week adherence (62% when neither accelerator was reported to 87% with both accelerators reported), clinic attendance (71%-89%), uninterrupted ART treatment (57%-85%), no TB symptoms (49%-70%) and viral suppression (60%-77%). CONCLUSIONS: Accessible and adolescent-responsive healthcare is critical to improving HIV-related outcomes, reducing morbidity, mortality and onward HIV transmission among AGYW. Combining these provisions can maximize benefits, especially for AGYW mothers.