The present study provides an overview of scientific developments made in the last decade in the field of green adsorbents focusing on the modifications in cellulose and starch and their applications such as drug delivery, wastewater treatment, and ion exchange. For this purpose, an introduction to the various methods of modifying cellulose and starch is first given, and then the properties, application, and future priorities of green adsorbents are also discussed. Methods of modification of cellulose and starch under homogeneous and heterogeneous conditions using modifiers with different properties are also described. Various methods for modifying cellulose and starch and the use of the obtained green adsorbents are reviewed. A comparison of the sorption properties of green adsorbents based on cellulose and starch and other adsorbents used in industry has also been carried out. Future perspectives on green adsorbents based on cellulose and starch are as also highlighted.