HBV is a major public health concern as it afflicts an estimated 350 million people worldwide. Studies are crucial and necessary to give us a better understanding of the epidemiology of the diseases in developing countries. A clearer picture of HBV/HIV prevalence in Africa is important in order to better educate the population and control these epidemics. This study estimated the seroprevalence of HBV/HIV coinfections among intending blood donors in Port Harcourt, Nigeria. In this cohort study, we collected blood samples from 178 intending blood donors who were confirmed to be HIV-seropositive at the University of Port Harcourt Teaching Hospital (UPTH) from September 2012 to June 2013. Commercial ELISA was used to assay for the presence of HBsAg among these subjects. The overall prevalence was found to be 6.7%. Sex and education (P < 0.05) were the main correlates in this study. Age was not statistically correlated (P > 0.05) in this study. We also observed a high overall HBV/HIV co-infection seronegativity of 93.3% among these blood donors. Group-specific seronegativity was also high ranging from 86.4-100.0%. Although the age groups (13-20, 21-35, and 36-66 years) insignificantly differed, none of their variables showed statistical association with the seronegativity. Our findings underscore the importance of screening for HBV/HIV among blood donors in developing countries, and particularly in sub-Saharan Africa, where the epidemics are still growing and a major public health concern.