A method of grafting well-defined and hydrolytically stable surface structures onto cross-linked poly(dimethylsiloxane) (PDMS) has been developed. In the first step, argon microwave plasma was used to introduce Si-H groups onto the surface. In the second step, allyltetrafluoroethyl ether was grafted to these Si-H groups using a platinum-catalyzed hydrosilylation reaction. The influences of the plasma parameters of power, pressure, and treatment time on the surface composition, both before and after the hydrosilylation step, were investigated by X-ray photoelectron spectroscopy and contact angle measurements. It was found that the pressure had little influence on the results, whereas the power and treatment time determined the rate of change in surface composition during the plasma treatment. The graft yield reached a plateau value corresponding to about 5% grafted molecules in the analyzed surface region. Hydrosilylation grafting of PDMS is a promising method to obtain biomaterials with hydrolytically stable structures covalently bound to the surface.