Abstract Background Optimal adherence is crucial for ensuring both therapeutic and preventative benefits of antiretroviral therapy (ART). Sub-optimal adherence is common in prisoners and little information is available about its predisposing circumstances in resource-limited settings. We explored lived experiences of inmates living with HIV (ILWH) and experiential accounts of service providers in South Ethiopia to identify barriers to and facilitators of HIV care use in the prison context. Methods We conducted qualitative in-depth interviewing with eleven ILWH and eleven service providers. Audio recorded interview data were transcribed verbatim in Amharic language, translated into English and coded based on emerging concepts. We employed a descriptive phenomenological approach to abstract meaning attributed to the prisoners’ lived experiences in relation to HIV care use and service providers’ experiential account regarding care provision as presented to our consciousness. Findings Several concepts emerged as barriers to HIV care use amongst ILWH in South Ethiopia including: limited access to standard care, insufficient health staff support, uncooperative security system, loss of patient privacy, a lack of status disclosure due to social stigma, and food supply insufficiency. In addition to a unique opportunity offered by an imprisonment for some ILWH to refrain from health damaging behaviours, the presence of social support in the prison system facilitated care use. Conclusions This study identified important structural and social contexts that can both hinder and enhance HIV care use amongst ILWH in South Ethiopia. Given the disproportionate burden of HIV in prisoners and the potential of transmission to others during and after incarceration, development of contextually-responsive strategies is required to address the barriers and to also strengthen the enablers.