Treatment of silyl ketene acetal-functionalized polysiloxanes with (trimethylsilyl)sulfonyl chloride, followed by hydrolysis in sodium bicarbonate, affords sulfonated polysiloxanes in high yield. The precursors are prepared by hydrosilation of poly(hydromethylsiloxane) or copolymers of dimethyl and hydromethyl units with silyl ketene acetals bearing a terminal olefin. Polysiloxanes having between 30 and nearly 100% sulfonate groups have been easily prepared. The sulfonated polysiloxanes are water-soluble and amphiphilic and are able to solubilize hydrophobic molecules such as pyrene as suggested by fluorescence spectra. Potential uses for these new polymers include surfactants and anionic dopants for conducting polymers.