Electrochemistry-controlled metal ion release is achieved using nanoparticle mixtures embedded into a silicone matrix. Synergistic metal ion release from silicone matrix filled with silver and copper nanoparticles as well as silver and gold nanoparticles embedded into silicone is investigated in terms of qualitative and quantitative influences. Results are compared to nanoparticle composites with only one metal. The mechanism enhancing the release of the less noble metal nanoparticle is based on the ion-mediated electrochemistry rather than on contact corrosion of both elements. A retardation as well as an enhancement of metal ion release is observed allowing a time- and rate-controlled design of bioactive nanocomposites.