Novel electroresponsive silicone elastomers modified with nitrile groups are presented, whose dielectric permittivity (epsilon') is tuned from epsilon' = 4.3 to epsilon' = 17.4. They are prepared in a one-step process starting from a high molecular weight poly(methylvinylsiloxane) to which polar nitrile groups and cross-links are introduced in thin films. Different ratios of butanethiol/3-mercaptoproprionitrile are used to vary the amount of nitrile groups in these elastomers, while 2,20-(ethylenedioxy) diethanethiol is used as a crosslinker. Because of the systematic nature of this investigation, we not only present promising elastic materials with remarkable dielectric, mechanical, and electromechanical properties but also provide a guideline for materials design aimed at dielectric elastomer actuator applications.