Background: Hepatitis B virus (HBV) infection caused 1.34million deaths in 2015, a number comparable to deaths caused by tuberculosis and HIV/AIDS combined. Previous prevalence of HBV was estimated to be 12.2%. Objective: This study aimed to determine Hepatitis B knowledge and risk perceptions among undergraduates of University of Calabar. Method: A cross-sectional descriptive study design was used and data were collected from 794 respondents using a semi-structured self-administered questionnaire. Results: The majority, 727 (91.6%) have heard about HBV, 678 (85.4%) correctly picked virus as cause of HBV, while 81(10.2%) picked malaria and consumption of dirty untreated water as the causes of HBV infection. On the mode of transmission, 598(75.3%) correctly picked sexual intercourse, 462(58.2%) picked sharing of sharp objects with infected persons. The majority, 562(70.8%) had good knowledge about the vaccines, while 232(29.9%) have poor knowledge, 506(63.7%) perceive HBV infection as treatable, 42(35.3%) respondents perceived HBV infection to be the same as HIV/AIDS, 615(77.4%) perceived it to be preventable, while 397(50.6%) respondents identified transfusion of unscreened blood as a risk factor for transmission of HBV. Summarily, 99(12.4%) respondents had poor knowledge, 213(26.8%) had moderate knowledge and 482(60.8%) students had good knowledge about Hepatitis B virus. Only half of the respondents, 398(50.2%) perceived HBV infection as a serious infection while 136(17.1%) have low perceived severity. Conclusion: Low perceived severity of HBV in a young, sexually active population may fuel increased prevalence if nothing is done to mitigate it. On-campus social marketing campaigns encouraging testing and preventive practices are recommended.