Carbon dots (CDs) have recently attracted extensive attention as a photothermal nanomaterial in tumor therapy. However, few CDs can achieve high photothermal conversion efficiency, especially in the near-infrared region. Beyond that, the targeting of CDs toward tumors is also an important issue to solve. In this review, some practical strategies are introduced to improve the near-infrared photothermal conversion efficiency of CDs through approaches including size adjustment, self-assembly, surface engineering, element doping, and semiconductor coupling to promote their application in tumor photothermal therapy. We encourage subsequent studies to focus on photothermal conversion based on these strategies and hope to establish an efficient CDs-tumor recognition and photothermal therapy platform, which is of great scientific interest in solving tumor-related problems.