Two-dimensional metal chalcogenides (2D MCs) present a great opportunity for overcoming the size limitation of traditional silicon-based complementary metal-oxide-semiconductor (CMOS) devices. Controllable modulation compatible with CMOS processes is essential for the improvement of performance and the large-scale applications of 2D MCs. In this review, we summarize the recent progress in plasma modification of 2D MCs, including substitutional doping, defect engineering, surface charge transfer, interlayer coupling modulation, thickness control, and nano-array pattern etching in the fields of electronic devices and optoelectronic devices. Finally, challenges and outlooks for plasma modulation of 2D MCs are presented to offer valuable references for future studies.