ObjectiveThis study evaluated the implementation fidelity (IF) of HIV/AIDS Care and Support (C&S) services for orphans and vulnerable children (OVC) at the African Network for Prevention and Protection Children against Neglect (ANPPCAN) Project, Gondar City, 2023.MethodA facility-based convergent parallel mixed-methods design was used to assess IF and identify factors influencing caregiver responsiveness. Quantitative data were collected from 424 OVC caregivers, 385 document reviews, 27 observations, and an inventory checklist. Qualitative data were obtained from five key informant interviews. Data were gathered concurrently, analyzed separately, and integrated during interpretation to provide a comprehensive view.ResultThe overall IF was 67.35%, with adherence at 81.5%, dosage at 45%, and caregiver responsiveness at 70.6%. Responsiveness was significantly associated with having separate waiting rooms, take-home materials, and friendly service delivery.ConclusionAlthough adherence was high, dosage was low and responsiveness moderate, indicating the need to strengthen service delivery components to improve implementation fidelity.