Highly advanced and sophisticated treatment processes are required to facilitate the safe and reliable reuse of wastewater in agriculture and industry, with the efficient removal of targeted and emerging organic and inorganic pollutants being necessary due to their severe health problems. Polymeric ion-exchange sorbents comprise one of the most significant scientific breakthroughs of the twentieth century. Their application in water softening, environmental remediation, wastewater treatment, hydrometallurgy, chromatography, bimolecular separations, and catalysis was recognized in numerous publications. The ion-exchange resins consist of different polymers and ligands covalently bound to the polymers. Polymers can be designed to possess a higher concentration of active sites and functional groups used for adsorption. Exceptional adsorbing ability is attributed to its numerous functional groups, including hydroxyl and amine, which facilitate the binding of diverse pollutants, encompassing organic and inorganic compounds, via multiple interaction types, making PDA a versatile and efficient adsorbent material. Natural polymers (such as cellulose and chitosan) that are biodegradable and eco-friendly are also used. Despite their potential, natural polymers face several limitations that restrict their effectiveness in applications like adsorption, making them less suitable for use in these contexts. This chapter addresses polymer-based ion-exchange sorbents for wastewater treatment, broadly classified into (I) natural and (II) synthetic polymers, and focuses on their exceptional ability to remove a wide range of pollutants, including dyes, heavy metal ions, organic compounds, and other harmful substances, due to their unique properties and features.