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Cancer poses a persistent global health challenge which demands more efficient treatments. Among various cancer treatment strategies, catalytic therapy, encompassing both chemotherapy and phototherapy, stands out due to its non-invasiveness and capacity to selectively target cancer cells. Catalytic therapy offers a unique approach to cancer treatment by leveraging the production of reactive oxygen species (ROS) via direct catalytic reactions or through photocatalytic processes. Carbon-based metal-free catalysts have gained increasing interest across a diverse range of sectors, from energy through environmental to biomedical technologies. With this context, recent developments in the field of nanotechnology and more specifically carbon-based metal-free catalysts (C-MFCs) have emerged as a transformative force in cancer diagnosis and treatment, due to their low cost, high catalytic efficiency and biocompatibility. Several types of carbon catalysts, such as carbon quantum dots, graphene and carbon nitrides, are evaluated for their potential in catalytic therapy. Of particular interest, graphene quantum dots show great potential as catalytic cancer chemotherapeutics. Among various reported photocatalysts, carbon nitride is particularly noteworthy due to its optimal biocompatibility, remarkable stability, and suitable band gap for visible light excitation, which make it a promising candidate for photodynamic therapy. The work presented in this thesis investigates the promising potential of carbon-based nanomaterials, particularly graphene quantum dots and carbon nitrides, in catalytic cancer therapy. This thesis studies in depth the catalytic chemotherapeutic effect of graphene quantum dots on cancer cell lines, producing dose-dependent cancer cell deaths. The responsible mechanisms have been identified as hydroxyl radical production from catalyzed hydrogen peroxide decomposition, which is correlated with the defect density in graphene quantum dots. For the first time, the defect-induced catalytic generation of ROS by C-MFCs in the tumor microenvironment was demonstrated and the associated catalytic mechanism elucidated. Subsequently, graphene quantum dots were combined with carbon nitride for photo-induced catalytic therapy to convert glucose into ROS to cause cancer cell death in cell cultures and a mouse xenograft model of breast cancer. This design provides an effective approach towards Near-infrared (NIR) responsive carbon-based photocatalysts for excellent photo-induced catalytic cancer therapy. Finally, a microelectrode-based electrochemical nanodevice has been developed for intracellular detection of ROS in single cells. This innovative tool also enables the potential for synergistic therapeutic applications by enhancing phototherapy through hydrogen gas generation. The clarified understanding of mechanisms at the single cell level thus obtained provides opportunities for further drug design and dose evaluation, along with the ability to improve further therapeutic efficiency via synergic effect with gas therapy. This work opens a new avenue for the development of safe and efficient catalytic nanomedicine. Overall, the research herein demonstrates that carbon catalysts show remarkable improvements in in-vitro and in-vivo models, setting the stage for further clinical investigations. This thesis signals an exciting new direction for the field of oncology by highlighting the transformative potential of integrating C-MFCs into cancer catalytic therapeutics and possible innovative cancer treatment strategies through the development of novel functional nanomaterials.