Abstract: To improve the tumor treatment effect and realize the combined photothermal and chemodynamic tumor treatment, a new nanocomposite material was designed: CeO₂@MnO₂@ICG. The material was synthesized by three steps. Firstly, the porous CeO₂ hollow spheres were synthesized by the self-templating method, the porous CeO₂ hollow spheres were coated with MnO₂ particles, finally, the CeO₂@MnO₂ complex was loaded with ICG to obtain CeO₂@MnO₂@ICG nanocomposites. In the CeO₂@MnO₂@ICG nanocomposite, the porous CeO₂ hollow spheres react with endogenous hydrogen peroxide within the tumor microenvironment to generate toxic OH, which causes tumor cell death. The encapsulation of MnO₂ particles further improves the catalytic performance of the composite and accelerates the CDT process. The ICG locally heats up the tumor cells under laser irradiation, the temperature increase promotes cancer cell death, and it can also promote the Fenton-like reaction, which makes the nanomaterial produce more ·OH and accelerate the apoptosis. The experimental results show that the CeO₂@MnO₂@ICG composites have superior photothermal properties and the ability to generate hydroxyl radicals. The tumor cell survival rate is only 18.3% under CeO₂@MnO₂@ICG composites. In conclusion, CeO₂@MnO₂@ICG composite nanomaterials are suitable for combined photothermal and chemodynamic tumor therapy.