Hemicellulose and their derivates as a branched and amorphous form of polysaccharides with a wide range of structural and functional properties are available in different plant resources e.g. agricultural residues, hardwoods, and softwood. A comprehensive investigation is adopted in extraction and processing techniques, including pretreatment methods (mechanical, chemical, enzymatic, and physico-chemical), isolation strategies like alkali extraction and hydrothermal methods, and advanced purification and characterization tools (FTIR, NMR, GPC). The chapter further investigates chemical and enzymatic modifications of hemicellulose, such as derivatization, crosslinking, and enzymatic tailoring, that enhance its functionality and expand its application spectrum. A thorough examination of hemicellulose derivatives such as esters, ethers, hydrogels, films, and oligosaccharides highlights their functional characteristics and performance attributes. The current study outlines their sustainable applications in food industry, pharmaceuticals, agriculture and integrating circular bioeconomy models by presenting future perspectives on green technologies.