This chapter delves into the sustainable production of biochar via microwave-assisted pyrolysis, emphasizing its role in waste valorization and long-term carbon sequestration. Unlike conventional pyrolysis methods, which are often hindered by uneven thermal distribution and low-energy efficiency, microwave irradiation ensures rapid and uniform heating, thereby enhancing both the quality and yield of biochar. A diverse array of biomass feedstocks—including agricultural residues such as rice husk, corn stalk, and bagasse, as well as urban solid wastes—are evaluated for their suitability in generating biochar with high surface area and favorable physicochemical properties. The influence of critical operational parameters—such as pyrolysis temperature, microwave power, and reactor configuration—on the structural and functional characteristics of the resulting biochar is systematically examined. Furthermore, the chapter explores a broad spectrum of biochar applications, ranging from soil amendment and carbon capture in agricultural systems to its emerging use in water purification, biomedical delivery systems, and microbial fuel cells. By integrating waste reduction with the generation of high-value carbonaceous materials, microwave-assisted pyrolysis is presented as a promising, scalable solution aligned with the principles of circular bioeconomy and environmental sustainability.