Introduction: For decades, viral diseases have been treated using medicinal plants and herbal practices in the northern part of Nigeria. Though scarcely investigated, these medicinal plants could serve as potential sources for novel antiviral drugs against emerging and remerging viral diseases. Therefore, this study is aimed at investigating the medicinal practices and plants used to treat emerging and re-emerging viral diseases including hepatitis, poliomyelitis, monkeypox, smallpox, yellow fever, Lassa fever, meningitis, and COVID-19 in some northern states; Katsina, Kebbi, Kwara and Sokoto states. Method: Administered questionnaires and oral interviews were used to collect information on medicinal plants, method of preparation of herbal formulations, diagnosis, and treatment of viral diseases. Medicinal plants were collected, botanically identified, and assigned voucher numbers. The plant names were verified using www. theplantlist.org, www.worldfloraonline.org and the international plant names index. Result: A total of 280 participating herbal medicine practitioners (HMPs) mentioned 131 plants belonging to 65 families. Plant parts such as roots, bark, leaf, seed, and fruit were prepared as a decoction, concoction, infusion, or ointment for oral and topical treatment of viral diseases. Moringa oleifera (75.3%), Elaeis guineensis Jacq. (80%), and Acacia nilotica (70%) were the most frequently mentioned plants in Kebbi, Kwara and Sokoto states, respectively. Conclusion: The study revealed scarcely investigated and uninvestigated medicinal plants used to treat hepatitis, poliomyelitis, monkeypox, smallpox, yellow fever, Lassa fever, meningitis, and COVID-19. Future studies should be conducted to determine the antiviral potency and isolate novel bioactive agents from these plants against viral diseases.