Nanotheranostics have begun at a phenomenal pace in the world of nanotechnology with the intention of bestowing the dual functionality of simultaneous diagnosis and treatment on nanomedicines in a single vehicle. During the last decade, numerous strategies have been employed for advanced, versatile theranostics application, with improved safety and efficacy to cure diseases at the earliest stage. Numerous therapeutic substances, such as drugs, genes, proteins and peptides, and so on, can be delivered in a smarter way with the aid of nanotheranostics for safe and precise targeting of diseased tissue to achieve higher efficacy. The current chapter thus presents an elaborated view related to the various nanotheranostics delivery systems, such as polymeric nanoparticles, liposomes, micelles, dendrimers, polymeric conjugates, carbon nanotubes, metal and inorganic nanoparticles, and so on, developed so far for theranostic application in the treatment of various diseases, along with their recent advancements.