Cancer is one of the most prevalent diseases with mortality rate considerably increasing every year. Conventional treatment strategies for cancer like chemotherapy suffer from the drawbacks of multiple-dose requirements and non-specificity of drug action. Moreover, the cost involved in the diagnosis and treatment is very high. Recently, the application of nanotechnology in the field of cancer has witnessed tremendous significance due to the unique size, shape, and surface properties of nanomaterials. With the intention to utilize biocompatible and biodegradable nanomaterials in cancer and reduce the non-specificity, approaches such as targeted nanotherapeutics came into existence. Besides having therapeutic potential, some materials demonstrate their applicability in bioimaging forecasting distinct optical properties. In this review, we have discussed the basics and principles guiding the design of different photo-triggered nanotheranostic materials used in cancer. Additionally, recent developments and advantages offered by the NIR-responsive photodynamic and photothermal agents along with their future scope have been presented. An overview of the toxicity and clinical prospect of photosensitive agents is also summarized. Overall, the field of photo-triggered cancer nanotheranostics has huge potential that can be clinically translated into an affordable and safe treatment approach.