Cancer has gained much attention because of slow development of advanced diagnostics and therapeutic strategies. So far, conventional procedures like surgery, radiation therapy and chemotherapy are only available options for cancer treatment which have various limitations. To overcome the limitations of conventional procedures, nanodiagnostics, and therapeutics are emerging approaches for localized diagnosis and treatment of cancer nowadays. So far, various bio-mimicking and stimuli active cancer theranostic platforms have been established but they are limited only for animal studies and their clinical translational progress is slow. Among various cancer theranostics platforms, photoresponsive systems have shown promising outcomes for cancer theranostics applications due to their specific physicochemical properties, biocompatibility, multifunctionality etc. Moreover, these photothermal agents in combination with diagnostics probes and surface functional targeting moieties demonstrate their synergistic response for site selective imaging and ablating cancer cells/tumor. Photoactive principles are rife and with increasing access to light irradiation setups, more the discovery of photoactive products, more would be the success reaped in cancer battle. This review highlights recent developments in cancer nanotheranostics with a special focus on photoactive functional nanotheranostics. Moreover, the challenges involved in clinical translation of photoactive materials along with their application in vivid areas of cancer nanomedicine and elucidate the future implications on photoactive therapy have been addressed here.