Abstract: Graphitic carbon nitride （g-C₃N₄）, a metal-free semiconductor featuring a unique band structure and excellent chemical stability, has attracted increasing attention in the field of antimicrobial materials in recent years. In the context of escalating bacterial infections, the rapid proliferation of drug-resistant pathogens, and the declining efficacy of conventional antibiotics, the development of novel antimicrobial technologies that are efficient and less prone to inducing resistance has become an urgent necessity. Antibacterial strategies based on photocatalysis and nanozyme-like catalysis offer new solutions to these challenges. Among them, g-C₃N₄-based material systems show remarkable potential across multiple antibacterial scenarios due to their tunable structure, high specific surface area, strong visible-light response, and good biocompatibility. The antibacterial mechanisms and application progress of g-C₃N₄-based materials are systematically summarized in this review. First, from a structural perspective, the layered framework of g-C₃N₄, its abundant surface nitrogen functionalities, and its electronically adjustable characteristics-achieved via doping, heterojunction construction, and defect engineeringare introduced. The charge-carrier separation efficiency and catalytic reactivity are significantly improved, forming the basis for high-performance antibacterial functionality. Regarding antibacterial mechanisms, this review outlines the multiple bactericidal pathways of g-C₃N₄-based materials. Their sheet-like structure can induce physical damage to bacterial cell walls, producing a certain degree of contact-based antibacterial action. Under light irradiation, g-C₃N₄ generates electron–hole pairs that participate in redox reactions, leading to the formation of reactive oxygen species （ROS）. These ROS disrupt cell membrane integrity and oxidize proteins, representing the core of g-C₃N₄-based photocatalytic antibacterial activity. Some metal-loaded or structurally modified g-C₃N₄ systems exhibit enzyme-mimicking catalytic behavior, simulating peroxidase- or oxidase-like activities and further enhancing antibacterial efficiency. The synergistic interplay of these mechanisms not only improves bactericidal performance but also reduces the likelihood of resistance development. In terms of practical applications, the advancements in four major areas are highlighted in this review: water purification, air disinfection, biomedical anti-infection, and functional antibacterial coatings. In water treatment, g-C₃N₄ enables efficient inactivation of waterborne pathogens under visible light and can be integrated with filtration membranes or adsorbents to construct continuous-flow disinfection systems. In air purification, g-C₃N₄-based catalytic filter layers effectively suppress airborne bacterial and viral transmission. In biomedical applications, g-C₃N₄ nanomaterials, benefiting from photodynamic or photothermal enhancement, are used for wound sterilization, implant-associated infection prevention, and skin regeneration. For antibacterial coatings, incorporating g-C₃N₄ into polymeric, metallic, or ceramic substrates yields durable, renewable, and environmentally friendly antimicrobial surfaces. Finally, the current advances and identifies future challenges are summarized in this review, including improving charge-carrier utilization, clarifying biosafety profiles, further elucidating multi-mechanism synergistic effects, and advancing large-scale material fabrication.