Treatment of aromatic alpha-phosphorylacrylate derivatives 1a-h with Mg turnings in the presence of trimethylsilyl chloride brought about facile and regioselective C-silylation to give the corresponding beta-silylated phosphonates 2a-h in excellent yields. The reaction took place smoothly for activated olefins possessing appropriate reduction potentials and may be initiated by electron transfer from Mg to 1a-h.