The existence of the several pollutants in water resources has led the water unfit for consumption or reuse, and eventually becoming one of the greatest threats to the environment and human health. Pollutants in water are not desirable even if they have less toxicity, therefore, they must be either removed or degraded. Despite several materials reported, polymeric materials have been widely suggested and used nowadays in water treatment applications to get rid-off the multiple pollutants. In this context, graphitic carbon nitride (g-C3N4), a two-dimensional organic polymeric material is emerging as effective adsorbent and photo-catalyst for the rapid removal and degradation of various pollutants from water. Therefore, this chapter is devoted to summarizing the latest applications of g-C3N4-based materials in water and wastewater treatment processes. Moreover, the challenges and future perspectives of the g-C3N4 is also discussed in this chapter.