Chemically modified electrodes, decorated with covalently tethered poly(ferrocenylsilane) – PFS chains, are fabricated. Robust, relatively dense redox-active films with a height of around 10 nm are successfully formed by reaction of poly(ferrocenyl(3-iodopropyl)methylsilane) with amine-terminated monolayers on silicon or gold surfaces. The electrochemical properties of the surface-immobilized PFS chains are studied using cyclic voltammetry (CV) and differential pulse voltammetry (DPV), both in aqueous and organic media. Information on the properties of these films as a function of redox state is gained using quantitative adherence measurements between the films and AFM tips. An ascorbic acid electrochemical sensor based on these surface-anchored PFS chains, exhibiting a high sensitivity and stability, was fabricated. The PFS layers described are easily derivatized, thus forming a platform for creating highly tailorable redox-active interfaces.