Background: The burden of COVID-19 and human immunodeficiency virus (HIV) are some of the major and persistent global health challenges of the twenty-first century. HIV and COVID-19 are expected to overlap in high HIV-burden countries, posing several public health challenges as a result. Prisons are overcrowded, have limited space for social distancing and have inadequate ventilation systems, making it difficult to contain the spread of COVID-19 in addition to the high-risk behaviours of inmates which contribute to the spread of HIV within these facilities. This study aimed to determine the prevalence of COVID-19 among inmates in a prison facility with a relatively high HIV burden in Port Harcourt, Nigeria; investigating potential risk factors and co-infection with HIV. Methodology: The study employed a descriptive cross-sectional study design sampling 200 inmates from the Port Harcourt Maximum Security Custodial Centre from July to December 2022. A well-structured questionnaire was administered via interviews in addition to screening for HIV-1/2 antibodies as well as COVID-19 antigens using rapid diagnostic test kits. Descriptive statistics and chi-square were carried out on the GraphPad Prism 9 software with statistical significance defined as a How to cite this paper: Mike-Ogburia, M.I.,