Nanotechnology has been the latest approach for diagnosis and treatment for cancer, which opens up a new alternative therapeutic drug delivery option to treat disease. Nanoparticles (NPs) display a broad role in cancer diagnosis and has various advantages over the other conventional chemotherapeutic drug delivery. NPs possess more specific and efficient drug delivery to the targeted tissue, cell, or organs and minimize the risk of side effects. NPs undergo passive and active mode of drug targets to tumor area with less elimination of the drug from the system. Size and surface characteristics of nanoparticles play a crucial role in modulating nanocarrier efficiency and the biodistribution of chemo drugs in the body. Several types of nanocarriers, such as polymers, dendrimers, liposome-based, and carbon-based, are studied widely in cancer therapy. Although FDA approved very few nanotechnology drugs for cancer therapy, a large number of studies are undergoing for the development of novel nanocarriers for potent cancer therapy. In this review, we discuss the details of the nano-based therapeutics and diagnostics strategies, and the potential use of nanomedicines in cancer therapy and cancer drug delivery.