The global farming sector not only produces foods, but it also generates substantial quantities of waste and byproducts, pretense environmental and economic challenges. This section describes the key role of microbial intervention as a sustainable approach for the valorization of these agricultural residual materials. Through harnessing the metabolic abilities of various microbes like bacteria, fungi, and yeasts, raw agricultural residues are to be competently converted into a varied range of value-added products. Significant microbial metabolic processes, like fermentation and bioconversion, are effective methods for making value-added products such as biofuels, organic acids, enzymes, biopolymers, vitamins, and probiotics. This approach improves the nutritional and functional quality of food and feed while also providing a sustainable way to recycle the waste valuable products. The chapter also highlights that microbial intervention is a keystone of a circular bioeconomy, presenting economically viable and biologically comprehensive metabolic pathways to recover agricultural sustainability, reduce waste, and create new profits.