Metal-free, low-cost, organic photocatalytic graphitic carbon nitride (g-C₃N₄) has become a promising and impressive material in numerous scientific fields due to its unique physical and chemical properties. As a semiconductor with a suitable band gap of ~2.7 eV, g-C₃N₄ is an active photocatalytic material even after irradiation with visible light. However, information regarding the toxicity of g-C₃N₄ is not extensively documented and there is not a comprehensive understanding of its potential adverse effects on human health or the environment. In this context, the term “toxicity” can be perceived in both a positive and a negative light, depending on whether it serves as a benefit or poses a potential risk. This review shows the applications of g-C₃N₄ in sensorics, electrochemistry, photocatalysis, and biomedical approaches while pointing out the potential risks of its toxicity, especially in human and environmental health. Finally, the future perspective of g-C₃N₄ research is addressed, highlighting the need for a comprehensive understanding of the toxicity of this material to provide safe and effective applications in various fields.