Molybdenum disulfide (MoS 2 ), a layered transitionmetal dichalcogenide nanomaterial, holds significant promise for various environmental applications, particularly in water treatment and remediation. This comprehensive review explores the critical roles of the 1T and 2H phases of MoS 2 in enhancing its performance for environmental applications. We provide a detailed overview of synthesis strategies and characterization techniques for MoS 2 with different phase compositions, and examine the aqueous stability and mechanisms of 1T and 2H MoS 2 under various environmental conditions. The review thoroughly evaluates the phase-dependent performance of MoS 2 in environmental remediation scenarios such as heavy metal removal, advanced oxidation processes, membrane separation, antibacterial actions, photocatalysis, dye adsorption, and environmental sensing. We delve into the underlying mechanisms driving these applications, highlighting the unique contributions of each phase. Our analysis underscores the importance of phase structure in optimizing the environmental functionality of MoS 2 . This review serves as a valuable resource for researchers aiming to leverage the distinct properties of MoS 2 phases to address critical challenges in water treatment and environmental remediation, offering insights into both fundamental mechanisms and practical applications.