Graphitic carbon nitride (g-C3N4), is an organic n-type visible light active semiconductor photocatalyst which gained significant attention in various applications taking advantage of its 2D structure, metal-free composition, high chemical and thermal stability. The characteristic features such as its tunable morphology, visible light absorption, tunable bandgap and ease of synthesis make this material promising in several applications. In this chapter, we have focused mainly on the latest developments of g-C3N4-based nanostructures toward photocatalytic pollutant degradation and antibacterial applications of g-C3N4. The physicochemical properties of g-C3N4 can be tuned appropriately to enhance the photocatalytic activity. This chapter discusses about the photocatalytic mechanism behind pollutant degradation and the bacterial disinfection mechanism in terms of reactive species generation. The photocatalytic degradation of dyes, antibiotics, organic pollutants and nitrogen monoxide (NOx) removal by g-C3N4 have also been discussed. The effects of g-C3N4 toward bacterial disinfection as well as bacterial response toward g-C3N4 have been discussed in the bacterial disinfection section. © 2023 Elsevier Inc. All rights reserved.