Treatment adherence among people living with human immunodeficiency virus (PLWH) is a critical determinant of viral suppression and improved quality of life. Medication literacy, as a key factor influencing adherence, is itself shaped by various psychosocial variables. Existing studies suggest that human immunodeficiency virus (HIV)-related stigma, self-efficacy, and trust in healthcare providers serve as significant mediators in the relationship between health literacy and treatment adherence. This review systematically explores how medication literacy affects treatment adherence in PLWH through intermediary psychosocial mechanisms such as depression, anxiety, and social support. By synthesizing current evidence, we aim to inform the development of targeted psychosocial interventions to enhance treatment outcomes and quality of life for this population. Our findings provide an evidence-based foundation for nursing practice and support innovative strategies in comprehensive HIV care.