The study developed a novel type of nitrogen-doped mesoporous carbon nanospheres (Fe/N-MCN) with single-atom and iron-cluster iron co-embedded, which exhibited multiple enzyme activities such as oxidase/peroxidase/catalase/glutathione oxidase, and was used in combination with photothermal therapy for the imaging and treatment of breast cancer. This nanozyme was synthesized through a controlled gradient concentration method, exploring the relationship between iron and nitrogen doping amounts and structure-activity, and selected Fe/N-MCN with excellent photothermal conversion performance and efficient enzymatic activity. These activities synergistically contributed to chemodynamic therapy, photodynamic therapy, and hypoxia relief. Additionally, Fe/N-MCN induced strong immunogenic cell death and sensitized tumor cells through reactive oxygen species, ferroptosis, and photothermal therapy, providing a new combined strategy for immunotherapy of breast cancer. At the same time, Fe/N-MCN also performed well in photothermal imaging, photoacoustic imaging, and magnetic resonance imaging, providing multimodal imaging guidance for tumor treatment and a multifunctional therapeutic platform for the inhibition of postoperative recurrence and metastasis of breast cancer. This work was mainly completed by doctoral student Yanhui Qin.