Noble metal nanomaterials, particularly gold (Au), silver (Ag), and platinum (Pt), and many more, have garnered significant attention in the fields of tumor diagnosis and treatment due to their unique optical properties, excellent biocompatibility, and high stability in physiological environments. In this chapter, the various preparation methods for noble metal nanomaterials are firstly introduced. Then, the optical properties of noble metal nanomaterials are described. Finally, we focus on the latest progress of noble metal nanomaterials in biomarker sensing and tumor treatment, such as photothermal therapy, photodynamic therapy, and many more. We hope that this review will guide the further development of noble metal nanomaterials and promote their practical applications in cancer diagnosis and treatment.