Nanoparticles offer unique advantages such as enhanced delivery efficiency, targeted release, and improved stability of antigens and therapeutic agents. This chapter tries to explore the use of various types of nanoparticles in the development of novel vaccines and immunotherapies. Nanotechnology provides a revolutionary approach in contrast to traditional immunotherapies, which frequently result in detrimental side effects because of hyperactivity, lengthy treatment periods, and inflated prices. Nanoparticles produce highly focused tissue delivery systems by utilising the better physicochemical characteristics of nanocarriers, such as a significant specific surface area that improves interactions with the immune system. There exists many promising nanoadjuvants and nanoparticulate delivery systems that demonstrate that the vaccine developers can now select specific adjuvants and delivery systems tailored to combat various infectious diseases. There are challenges associated with the development of these nanoparticle-based vaccine and therapy development, including manufacturing, scalability, and regulatory hurdles. The chapter concludes by envisioning future directions and the transformative potential of nanoparticle-based approaches in revolutionizing healthcare and disease management.