Purpose: To determine factors that influence people living with HIV to engage in internet-based HIV information seeking behaviour in selected Tanzanian public regional hospitals. Methodology: We conducted a questionnaire-based survey to 221 PLHIV in two regional public hospitals in Mwanza and Dar es Salaam, Tanzania. We assessed the validity and reliability of the measurement model by using Exploratory Factor Analysis (EFA); while we used hierarchical regressions to examine the research hypotheses by using SPSS. Findings: The study found that there is low usage of internet (24.3%) to search online HIV information. Factors related to attitude and information source accessibility predicted usage intentions of Internet, while facilitating conditions, information source accessibility and usage intention of internet determined actual use of internet among PLHIV. Age moderated the effects of information source quality and social influence on usage intention of internet, and the effects of the information source accessibility and social influence on actual use of Internet. The findings imply that younger PLHIV were more likely to use internet to access HIV information than the older respondents due to perceived ease of accessing information and quality of the online content. Further, older PLHIV were more influenced by the views of others when making decisions to use internet. Practical implications: Health care providers and libraries need to conduct regular studies on health needs of patients, and promote benefits of accessing online information; website designers need to design user friendly databases; public libraries need to include a section on health information; hospital and public librarians need to provide catalogues of health information resources on their websites; and health care providers need to improve technological infrastructure. Originality: This is a comprehensive study that provides empirical findings to better understand the HIV information seeking behavior from actual internet users, particularly factors that may influence people living with HIV to seek online information in Tanzania.