Surgery followed by adjuvant chemotherapy is a reliable therapy for colon cancer, but is associated with side effects and risks. Recent advancements in nanobioengineering in the form of targeted nanoparticles, cubosomes, liposomes, nanosheets, nanorods, quantum dots have generated substantial advancements in theranostics of colon cancer decreasing the cytotoxic drugs' side effects. We describe a facile mechanism of preparation of hybrid nanocomposite encompassing Au and Ag. Preparation of hybrid nanocomposite is one step process which may be easily escalated. The nanocomposite was characterized using transmission eleactron microscopy, energy dispersive X-Ray spectroscopy, X-ray photoelectron spectroscopy, Fourier transform infra-red spectroscopy, UV-Vis spectroscopy, photoluminescence and cytotoxic studies. In-vivo studies were carried out in Balb/c mice. Photothermal heating experiments in HeLa cells were promising and the characterization studies clearly indicated the formation of hybrid nanocomposite. In-vivo experiments confirmed the efficacy of treatment, along with involvement of epigenetic regulation, which may be helpful in translation from research to clinical applications. Colon/colorectal cancer is the fourth most dangerous form of cancer causing high mortalities around the world 1. Surgical interventions followed by adjuvant chemotherapeutic sessions remain until today, the only option for treatment of solid tumors. Other treatments including transplant of stem cell, immunotherapy, hormonal therapy, targeted drug through nanoparticles have been suggested. However, these may be accompanied by side effects like chances of recurrence of metastatic tumors, unendurable cytotoxicity, non-restricted annexations in various other tissues and extremely low bioavailability of encased drugs 2,3. Hence, there is an immediate need for the development of new theranostic options for these metastatic tumors with minimal side effects. Photothermal therapy has emerged as an alternative option for cancer therapeutics and the reasons that make it such an attractive option are manifold. This therapy is highly efficient, can be achieved in a controlled manner and is minimally invasive 2. Photothermal therapy involves ablation of the cancerous tissues utilizing laser 4-7 , high intensity ultrasonography, microwave or radiofrequency radiation 8,9. Optically sensitive mediators are used to endogenously absorb the optical energy and transform it into thermal heat using near-infrared (NIR, 650-1025 nm) radiation. The heat energy which is so generated destroys the cellular membranes and causes protein denaturation causing cancer cell death 2,10,11. However, the procedure is generally restricted by the precision of imaging, applicator utilized for the therapy and the shape of the applicator whether conical or round as this is directly related to energy deposition 4. Hence for precise and effective therapy, the mediators must absorb energy in the NIR spectrum and must be absorbed at the specific cancerous tissue. These must also fa...