Herein, we describe the fabrication of chitosan stabilized multifunctional hafnium oxide@gold core‐shell nanoparticles (HAT NPs) (≈12 nm). The developed nanoparticulate system offers multimodal action by providing stimuli responsive anticancer drug delivery along with imparting radiosensitization to cancer cells, thereby protecting surrounding normal tissues from damage. HAT NPs exhibit good capability of loading doxorubicin (DOX), an anticancer drug with ≈ 87% encapsulation efficiency. DOX loaded HAT NPs are able to release ≈ 91% DOX under GSH reducing conditions that is a representative of the cancer cell microenvironment. The cytotoxicity of the developed DOX loaded HAT NPs was tested against breast cancer cells (MDA‐MB‐231), showing higher cytotoxicity as compared to free DOX. Additionally, the ability of HAT NPs to generate ROS activity upon irradiation by gamma radiations (0.5 & 5 Gy) was also analysed in cancer cells to demonstrate the ability of synthesized system as a potent candidate to present radiosensitization. Further, in vivo biodistribution studies was executed to understand the tissue specific retention of HAT NPs for their future utility in targeted cancer treatment applications.This article is protected by copyright. All rights reserved