The deacetylation of chitin, a biopolymer produces a semi synthetic amino polysaccharide called chitosan. Chitin is primarily derived from natural sources such as terrestrial organisms, aquatic organisms, microorganisms such as fungi, and crustacean shell waste materials. Chitosan is a co-polymer of glucosamine and N-acetyl glucosamine units connected by 1–4 glycosidic bonds obtained by N deacetylation of chitin. It has unique characteristics like biocompatibility, biodegradability and non toxicity. In comparison to other natural polymers, chitosan and its derivatives are the promising green chelants among natural polymers. pH effect, ion selectivity, polymer chain and deacetylation degree are the different factors which influence the chelate formation. Chelation is due to chitosan amino groups, in which nitrogen acts as an electron donor. Chelating action of chitosan and its derivatives is fetching great attention in heavy metal remediation of contaminated soil, waste water treatment, phytoremediation, nutrient delivery and crop protection fields. Chitosan and its derivatives have promising future in the development of sustainable agriculture practices.