PTT (photothermal therapy)/PDT (photodynamic therapy) has unique advantages, such as its minimally invasive nature and clinical relative safety, and is considered a promising approach for cancer diagnosis and treatment. However, the therapeutic efficacy of phototherapy is often limited by the limited depth of light penetration and the low targeting of phototherapeutic agents. Recently, photoresponsive inorganic nanomaterials have flourished in the fields of PTT and PDT in cancer, providing a possible approach to enhance phototherapeutic potency. This review summarizes the recent research progress of common photoresponsive inorganic nanomaterials in the field of PTT and PDT and their diagnosis in cancer, involving noble metal nanoparticles, sulfide nanomaterials, oxide nanomaterials, and carbon nanomaterials. It focuses on the therapeutic and diagnostic performance of PTT and PDT of these inorganic nanomaterials and provides strategy improvements for expanding the drug delivery application of PTT/PDT. Finally, the future research and development of photoresponsive inorganic nanosystems for the treatment and diagnosis of PTT/PDT in cancer are discussed, and the possible opportunities and challenges are discussed.