Transition metals, e.g., platinum (Pt), possess unique physicochemical and biological characteristics due to the presence of half-filled d-orbitals, with which they can exhibit variable oxidation states and catalytic ability and they can form complex and colored compounds. Besides, they display exceptional surficial properties that play a vital role in automobile catalytic converters and petrochemical cracking applications. However, catalysis is versatile and pivotal among the others that attracted attention owing to its diversity, which is further categorized as homogeneous, heterogeneous, and biocatalysts in terms of their functionality. Owing to their distinctive hard complex, heavy, and less-reactive nature, Pt nanoparticles (NPs) are very good catalytic materials and their compounds attracted considerable interest in the biomedical field of applications, such as nanomedicine, photothermal therapy, radiation dose enhancement, computed tomography (CT), and X-ray. Furthermore, Pt-based materials possess excellent antioxidant, antibacterial, antiviral, and anticancer nature, enabling them as nanocarriers, nanozymes, and nanosensors for diagnostic purposes. Cancer is one of the most intensely researched fields, where Pt derivatives, such as cisplatin, carboplatin, and oxaliplatin, are widely utilized in clinical research to combat various drug-resistant bacteria and to lessen the undesirable side effects of radiation and chemotherapy. Pt-based compounds have great potential and their drugs are being examined extensively ever since their anticancer activity was discovered. They have unexplored potential for the fabrication of drugs that are useful for viral infections. As a result, several novel Pt compounds were produced, some of which have intriguing antiviral characteristics. This chapter aims to demonstrate the potential use of Pt NPs in antibacterial and antiviral applications.