Nanodesigning and nanoengineering are key techniques in organic-inorganic synthesis to develop tailor-made materials for advanced applications. Here, we report on a nanocapping technique that is the first to achieve an "ionomer capped inorganic nanoparticle", and a nanohybrid material composed of a perfluorosulfonated ionomer (PFSI) and a zirconia precursor. The capping between the PFSI and the zirconia precursor was observed only under a narrow range of conditions, and we achieved this by carefully controlling the reaction conditions as well as the amount of chelating agent, catalyst concentration, and PFSI concentration. The capped nanoparticles were analyzed using DLS, TEM, and SAXS techniques. Capping greatly decreased the dimensions of the PFSI to the size of the zirconia nanoprecursor, and also broke down the rigid microphase-separated original structure of the PFSI. Our results also suggest that PFSI was adsorbed on the zirconia precursor via a multipoint adsorption, thereby preventing nanoparticle aggregation. Due to the effective nanocapping, an inorganic concentration as high as 50 wt% could be incorporated into the PFSI matrix without any aggregation occurring. The stability of the nanodispersion was evaluated over a period of one year and was found to be very stable.