Microwave technology has become a prominent and sustainable method for isolating and chemically modifying natural polysaccharides, mainly from plant biomass. It offers rapid, uniform, and selective heating, significantly reducing reaction times and energy use compared with traditional methods. During isolation, microwaves enable the effective extraction of high-purity polysaccharides using smaller amounts of milder solvents, aligning with green chemistry principles. For chemical modifications, microwave activation enhances reaction efficiency, lowers reagent consumption, and minimizes byproduct formation. These improvements produce polysaccharides with enhanced properties, such as increased solubility, antimicrobial activity, and tailored functionalities, broadening their use in food, cosmetics, pharmaceuticals, and biodegradable packaging industries. Compared with conventional heating, microwave-assisted processes have been reported to reduce energy demand and the associated carbon footprint. Future developments include integrating microwaves with other activation techniques such as ultrasound or enzymatic catalysis to boost efficiency and selectivity. Utilizing residual biomass as a polysaccharide source also presents a promising route toward sustainable and circular economy practices, meeting rising demands for eco-friendly materials and clean technologies. Overall, microwave-assisted processes are establishing themselves as vital tools in green chemistry, driving innovation in renewable materials and sustainable industrial applications.