The growing concern over water pollution due to industrialization and urbanization has intensified the need for effective wastewater treatment methods. With its high efficiency, simplicity, and cost-effectiveness, adsorption has emerged as a preferred technique for removing a wide range of contaminants from wastewater. This chapter explores the potential of surface-functionalized MXenes, a novel class of two-dimensional materials, as advanced adsorbents for wastewater treatment applications. MXenes, characterized by their large surface area, high electrical conductivity, and rich surface chemistry, can be tailored through various surface functionalization techniques to enhance their adsorptive properties. The functionalization approaches, including chemical modification with small molecules, polymers, and other agents, allow for tuning MXenes' surface properties, thereby improving their selectivity, capacity, and stability in contaminant removal. The chapter reviews adsorption studies for various contaminants, including heavy metals, dyes, and organic compounds. It discusses the adsorption mechanisms in depth, such as ion exchange, electrostatic interactions, and surface complexation, highlighting how different functional groups on MXenes contribute to efficiently removing specific pollutants. The interplay between the MXene surface chemistry and the nature of the contaminants is thoroughly analyzed to illustrate the versatility and effectiveness of these materials in diverse wastewater treatment scenarios. The challenges associated with using surface-functionalized MXenes in real-world applications are discussed. Further, future directions indicate the need for ongoing research to optimize MXene properties, improve functionalization techniques, and develop scalable production methods.