Water is a very essential natural resource on the earth and water bodies facing major due to the addition of various contaminations. Photocatalytic degradation of dyes, chemicals, heavy metals and other impurities in water attaining more importance in recent research. Since the past few decades, various materials have been used for the process of photocatalytic activity. Desirable low-cost dressing materials such as natural carbohydrate polymer nanocomposites (CPNs) used for the photocatalytic agents for degrading the impurities in water. Moreover, carbohydrates like pectin, chitosan, and alginates etc., in combination with polymers with polymer and metals improves the affinity between the mental nanoparticles and polymer. Carbohydrates are acts as capping agents for the synthesis of polymer nanocomposites. Hence, carbohydrate mediated polymer nanocomposites result good photocatalytic activity. The book chapter includes synthesis of various CPNs and photocatalytic efficiency of fabricated CPNs.