The perennial herbaceous grass Miscanthus × giganteus (M×g) has gained increased interest for its adaptability to various environmental conditions and potential applications in remediating and enhancing the quality of contaminated and/or degraded soils. This chapter sheds light on the multifaceted roles of the plant in the treatment of contaminated soils (organic pollutants and inorganic trace elements). The physiological and biochemical defense mechanisms of the plant against various contaminants are discussed, highlighting its ability to tolerate and negate the adverse environmental stressors. Moreover, the chapter targets the processes through which M×g facilitates the degradation of organic contaminants, such as hydrocarbons and pesticides, and stabilizes trace elements, mitigating their mobility and bioavailability. With respect to the soil phytoremediation, the chapter explores the plant’s contributions in enhancing the soil physicochemical and biological properties, such as soil structure, pH, and nutrient availability, along with the microbial biomass, diversity, and activity. The role of M×g in soil carbon sequestration and nitrogen fixation is also discussed, and thus its contribution to climate change mitigation, through studying the variations in soil organic carbon and nitrogen cycling. This chapter presents a comprehensive attempt to condense and summarize the published data on the pivotal role of M×g in abating the destructive effects of soil contaminants on the soil ecosystem and consequently the environment, offering valuable insights for researchers and practitioners in soil remediation and sustainable land management.