Compromised immune individuals are chiefly affected by transmitted infectious agents or toxicants reflected by the annual demise of over 17 million globally. The conventional chemotherapy suffers from its high-dose requirements, poor bioavailability, low therapeutic indices, adverse side effects, development of multi-drug resistance, disability of crossing the biological barriers, and non-specific targeting. To overcome all the barriers, nanotechnology-based drug delivery systems have attracted attention as probable nanomedicine for the treatment of diseases. Manganese nanomaterials (MnNMs) such as manganese, manganese oxides and phosphate nanoparticles have gained interest owing to their suitable nanosize structures, easy surface modifications capability, cargos-vectoring ability, oxidative and non-oxidative microbicidal and anti-carcinogenic activities, photothermal effectivity and easy membrane penetrating ability to damage the cells. This review illustrates the recent advances regarding their synthesis, functionalization, mechanism of action, therapeutic efficacies, toxicity, biodistribution, pharmacokinetics and elimination for the application in targeted delivery as potential therapeutics against infectious diseases and cancer.