The noble metal nanoparticles sandwiched between the stable inorganic core and the thin polymer shell could not only enhance their stability, but also cut short the diffusion route of the outside reactants through polymer shell toward encapsulated noble metal nanoparticles, which has drawn great attention. However, weak compatibility among inorganic core, polymer shell, and noble metal nanoparticles makes the preparation of noble metal-confined hybrid catalysts complicated, which limits the popular application of these noble metal-based catalysts. A facile method has developed to fabricate core-shell Fe2O3@PEDOT/Pt nanocatalyst with tiny Pt nanoparticles highly dispersed in the polymer shell by one-step simultaneous redox deposition strategy. The confinement effect and strong coordination ability of the thin sulfur-enriched polymer shell prevents the migration and agglomeration of Pt nanoparticles during the catalytic process and improves the stability of the catalyst. The catalyst shows outstanding catalytic activity and relatively good stability towards the reduction of nitroaromatic compounds. The simple method solves the problem of poor compatibility between the inorganic core, the polymer shell, and the noble metal nanoparticles confined in the shell material to some extent. Furthermore, our strategy could be extended to one-step preparation of Fe2O3@Polymer@Pt hybrid materials with core-shell structure.