Cancer has become a major global health challenge, and current treatment modalities, including surgery, radiotherapy, chemotherapy, targeted therapy, and immunotherapy, all have inherent limitations. In recent years, nanotechnology, particularly carbon-based nanozymes, has emerged as a promising approach in cancer therapy. Carbon-based nanozymes, as a novel class of catalysts, offer excellent biocompatibility, low toxicity, and good stability. They can catalyze reactions that generate reactive oxygen species (ROS), which directly kill cancer cells or enhance the bioavailability of therapeutic agents, thereby improving treatment efficacy. Compared to conventional nanozymes, carbon-based nanozymes are easier to synthesize, more versatile, and exhibit greater durability, making them highly promising for cancer therapy. This review aims to provide a comprehensive overview of the classifications, catalytic mechanisms, and applications of carbon-based nanozymes in cancer therapy, with a focus on catalytic and multimodal treatment strategies. It highlights the unique advantages of carbon-based nanozymes and discusses the current state of research in this field. By synthesizing the available literature, this review offers valuable insights for researchers and encourages further exploration of carbon-based nanozymes in cancer treatment.