Hepatitis B (HBV) and Hepatitis C (HCV) are significant global public health burdens associated with liver cirrhosis, liver cancer and are responsible for over a million deaths yearly. Prisons and other confined facilities offer opportunities for the acquisition and transmission of infectious diseases such as hepatitis B and C during and after imprisonment. This study aimed to investigate the seroprevalence of Hepatitis B and Hepatitis C as well as their associated risk factors among inmates in the Port Harcourt Maximum Security Custodial Centre. A cross-sectional study was conducted among inmates incarcerated in the Port Harcourt Maximum Security Custodial Centre from July to December 2022, and 200 consenting subjects completed a structured questionnaire in addition to screening for the presence of HBsAg and anti-HCV antibodies. Data generated from this study was represented as frequency and percentages, and inferential statistics were carried out using chi-square with the aid of GraphPad Prism Software Version 9. Statistical significance was defined as a p-value of less than 0.05 at a 95% confidence interval. The seroprevalence of HBV was 4% while 3.5% was recorded for HCV with no cases of co-infections reported. HBV seroprevalence was significantly associated with blood oath and a history of surgery (p < 0.05) while HCV seroprevalence was significantly associated with a history of blood oath, sex with non-marital partners as well as a history of illicit drug use (p < 0.05).