Redox-responsive polyvinylferrocene-grafted silica nanoparticles have been used for modulating the catalytic activity of surface attached Grubbs second generation type catalysts for the ring opening metathesis polymerization (ROMP) of norbornene monomer. A facile and very efficient protocol for the modification of living polyvinylferrocene chains was developed to introduce a suitable functional group for the intended "grafting onto" approach. Grafted particles were characterized by using TEM, SEM/energy dispersive Xray spectroscopy (EDS), XPS, small-angle X-ray scattering (SAXS), dynamic light scattering (DLS), and cyclic voltammetry, revealing both the presence of reclox-responsive polymers and the presence of Grubbs catalyst in the particle exterior. Chemical oxidation protocols for immobilized polymers were applied to deactivate surface attached catalysts in ROMP protocols, while chemical in situ reduction immediately led to catalyses reactivation.