Adherence to antiretroviral therapy (ART) is crucial for managing HIV infection effectively in resource-limited settings such as Kenya. The study employed a mixed-methods approach combining qualitative interviews and quantitative surveys to gather insights from patients and healthcare providers in Nairobi hospitals. Findings indicated that stigma and limited access to healthcare facilities were significant barriers to ART adherence, with over 40% of participants reporting non-adherence due to these factors. Health psychology interventions focusing on reducing social stigma and improving accessibility showed promise in enhancing ART adherence rates. Community-based health education programmes should be integrated into healthcare services to address the identified barriers effectively.