A novel stimuli-responsive material is reported with the self-healing antifouling surface via 3D polymer grafting. The self-healing surface is generated from a polymer network and polymeric chains grafted both to the surface of the network and inside the host network material. In the conventional approach to an antifouling surface via grafting of polymer brushes, the degradation and detachment of grafted polymeric chains would expose the underlying layer, leading to a loss of the antifouling effect. If a substantial fraction of the grafted polymers is degraded and detached, the proposed material with 3D polymer grafting retains its antifouling property due to the spontaneous (driven by an emerging gradient in a chemical potential) replacement of detached or damaged polymeric chains with segments of the chains stored inside the film in proximity to the interface. The pH-responsive poly(2-vinylpyridine) films with the 3D grafting of poly(ethylene oxide) in physiological conditions (pH 7.4 and 37 °C) demonstrate a 4-fold increase in longevity of antifouling behavior than the material with the surface grafted polymer. At the same time, the 3D grafted responsive films retain their pH-responsive properties. The proposed 3D polymer-grafting can be carried out on various surfaces (polymers, nanofiber mats, nanoporous inorganic materials, etc.) and, hence, can aid in the design of advanced biointerfaces for biomedical and biotechnological applications.