Light-based theranostics have become indispensable tools in the field of cancer nanomedicine. Specifically, near infrared (NIR) light mediated imaging and therapy of deeply seated tumors using a single multi-functional nanoplatform have gained significant attention. To this end, several multi-functional nanomaterials have been utilized to tackle cancer and thereby achieve significant outcomes. The present review mainly focuses on the recent advances in the development of NIR light activatable multi-functional materials such as small molecules, quantum dots, and metallic nanostructures for the diagnosis and treatment of deeply seated tumors. The need for improved disease detection and enhanced treatment options, together with realistic considerations for clinically translatable nanomaterials will be the key driving factors for theranostic agent research in the near future. NIR-light mediated cancer imaging and therapeutic approaches offer several advantages in terms of minimal invasiveness, deeper tissue penetration, spatiotemporal resolution, and molecular specificities. Herein, we have reviewed the recent developments in NIR light responsive multi-functional nanostructures for phototheranostic applications in cancer therapy.