Highly catalytically active yolk-shell Au-CeO2@ZrO2 nanoreactors (gold core encapsulated into porous zirconia shell and doped by ceria) for the 4-nitrophenol reduction to 4-aminophenol were synthesized. Au cores encapsulated into SiO2 (Au@SiO2) were decorated with ceria via injection of ceria precursor into a void space of silica shell (formed through surface-protected etching of silica by hot water) with its subsequent hydrolysis and thermal treatment (Au-CeO2@SiO2). Au-CeO2@ZrO2 nanoreactors were obtained using Au-CeO2@SiO2 as a template and replacement of SiO2 by ZrO2. The nanoreactors were characterized by STEM-EDS, in situ and ex situ UV-Vis spectroscopy, and N2 thermal adsorption. The catalytic activity for decorated Au-CeO2@ZrO2 nanoreactors in the 4-nitrophenol reduction into 4-aminophenol was found to be ~3 times higher than for non-decorated Au@ZrO2 nanoreactors. The herein proposed route of nanoreactor core decoration may be applied for the synthesis of nanoreactors with cores modified with different materials in order to make them effective for different catalytic reactions.