A practical and efficient methylthiolation that employed the typical Bunte salt sodium S-methyl sulfothioate as the sulfur source was described. This reagent could react with a variety of compounds such as alkynes, 1,3-diketones, thiols, selenol and H-phosphine oxides, affording methylthiolated products in moderate to excellent yields. The advantages such as easy preparation, air- and moisture-stability and high tolerance of functional groups demonstrated the potential of this reagent to be widely applied in organic synthesis. Notably, the robustness of this reagent was demonstrated by the late-stage modification of drug molecules of erlotinib.