With the rapid development of precision medicine and the continuous evolution of smart wearable devices, photothermal materials (PTMs) are experiencing a tremendous opportunity for growth. PTMs can efficiently convert light energy into heat to achieve localized thermal therapy for specific cells or tissues, offering advantages of minimal invasiveness, high selectivity, and precise targeting. Furthermore, PTMs can serve as molecular imaging probes and smart drug carriers, integrating multiple functions such as bioimaging and drug delivery to realize the visualization and controlled release of therapeutic processes. Due to their photothermal conversion properties, PTMs are able to provide dynamic temperature regulation for smart clothing, thereby enhancing the comfort of the wearer. Furthermore, integrating a photothermal system with thermoelectric materials allows for the recovery of waste heat for electricity generation, and build self-powered intelligent sensing networks. This not only addresses the challenge of energy supply but also expands the application scenarios of wearable devices. This review provides a systematic explanation of photothermal conversion mechanisms, explores the characteristics of excitation light commonly used in photothermal therapy, and presents a scientific classification and summary of PTMs. It offers a comprehensive overview of the latest research advances in the biomedical applications of PTMs, including antibacterial therapy, tumor treatment, bone repair, bioimaging, and smart wearable devices. Finally, it analyzes existing challenges and looks ahead to future directions, providing valuable insights for the continued development of related fields.