MXene is an emerging two-dimensional nanomaterial with tunable composition, controllable structure and excellent photothermal properties. MXene can absorb incident light and efficiently convert it into thermal energy, which provides a new way for the effective utilization of solar energy, and its incorporation into polymer matrix can give polymer-based composites excellent photothermal properties and broaden the scope of composite applications, and thus is widely studied. Polymer-based MXene composites with photothermal properties have a wide range of promising applications in desalination, personal thermal management, photothermal antibacterial and photothermal tumor treatment. This paper summarizes the preparation methods of MXene and polymer-based MXene composites, introduces the photothermal conversion mechanism of photothermal materials, reviews the research progress of polymer-based MXene composites in photothermal conversion, and finally outlooks the challenges and future development directions of polymer-based MXene composites with photothermal properties in applications.