With the rapid advancement of the electronics industry, the demand for new electromagnetic interference (EMI) shielding materials has grown substantially in recent decades. In response, a wide range of novel materials are being investigated as alternatives to conventional metals. Consequently, lightweight EMI shielding materials designed for miniaturized and highly integrated electronic devices have attracted increasing attention. Two-dimensional (2D) transition metal dichalcogenides (TMDs) offer several advantages—such as excellent thermal and chemical stability, tunable electrical conductivity, unique layered structures, and ultrathin thickness—making them promising candidates for EMI shielding. This review summarizes recent advances in TMDs and their nanocomposites for EMI shielding, highlighting synthesis strategies and offering in-depth analysis of shielding effectiveness, thickness, flexibility, and underlying mechanisms. In addition, the current challenges and future prospects of TMD-based EMI shielding materials are discussed.