Since decades, conventional diagnosis and treatment strategies for cancer have attracted major attention despite of their expensive and time-consuming process. Moreover, conventional contrast and therapeutic agents have been suffering with various side-effects such as low radiodensity and image resolution, rapid clearance, nonspecific bio-distribution, poor tumor accumulation, heavy and multiple dose requirements, nephrotoxicity, uncontrolled exposure of high electromagnetic radiations, whole body scans etc. On the other hand, high electromagnetic radiation exposure may cause inflammation, body rashes and mutation in healthy cells leading to other diseases. Although, the technical modalities are growing fast, the progress of new cancer medicines is slow. Therefore, nanosized theranostics are gaining momentum as a concept for localized imaging and solid tumor ablation. Interestingly, nanotheranostic probes have been already recognized as clinical “weapon” for localized cancer nanomedicine. So far, numerous functional nanohybrids have been applied for targeted imaging and stimuli active therapies. Hence, nanosized diagnostics and therapeutics systems have been recognised as potential probes for combination therapies, image guided tumor regression, deep tissue visualization, localized diagnosis and tumor ablation, manipulating tumor microenvironment etc. Integration of nanodiagnostics and therapeutics within a single system represents a major achievement in cancer nanomedicine. Overall, localized and stimuli active nanosized theranostic platforms have proved its superiority over conventional therapies. This article will introduce and highlights the recent advancements of localized nanotheranostic approaches and new developments in cancer nanomedicine.