Hepatitis B virus reactivation (HBVr) can be a serious clinical complication that has not been fully characterized in terms of the drugs associated with this adverse effect. Leveraging the expansive data available in the FDA Adverse Event Reporting System (FAERS) and the Japanese Adverse Drug Event Report (JADER) databases, we conducted a retrospective analysis to identify drugs significantly linked to HBVr using three disproportionality analyses. Our study identified 44 drugs associated with HBVr, of which 35 did not have warnings in their product labels. The majority of these drugs were antineoplastic and immunomodulating agents, with a tendency for early occurrence of HBVr, particularly among antineoplastic agents and systemic corticosteroids. Additionally, entecavir, tenofovir disoproxil and tenofovir alafenamide demonstrated better safety profiles in preventing HBVr. These findings enhance our understanding of the demographic characteristics of patients at risk for HBVr, the drugs that pose a high risk for HBVr, the timing of such events, and the appropriate preventive medications. This knowledge contributes to the development of better prevention and treatment strategies, ultimately optimizing patient outcomes.