During the last decade, hydrogels have been used as potential adsorbents for removal of contaminants from aqueous solution. To improve the adsorption efficiency, there are numerous different particles that can be chosen to encapsulate into hydrogels and each particle has their respective advantages. Depending on the type of pollutants and approaching method, the particles will be used to prepare hydrogels. The hydrogels commonly applied in water/wastewater treatment was mainly classified into three classes according to their shape included hydrogel beads, hydrogel films, and hydrogel nanocomposites. In review of many recently research papers, we take a closer look at hydrogels and their applications for removal of contaminants, such as heavy metal ion, dyes, and radionuclides from water/wastewater in order to elucidate the reactions between contaminants and particles and potential for recycling and regeneration of the post-treatment hydrogels. Graphical abstract ᅟ