Herein, we have rationally designed and originally fabricated a high-performance monolith catalyst based on 3D hierarchical foam-like Fe₂O₃@CuO_x for selective catalytic reduction (SCR) of NO with NH₃. The Fe₂O₃@CuO_x foam catalyst was synthesized by calcining the Cu foam in air first to form CuO_x foam with CuO_x nanowire arrays on the surface and then the Fe₂O₃ could be in situ formed on the surface of CuO_x through the reaction in the interfacial region between the aqueous solution of Fe²⁺ and CuO via a hydrothermal method. This catalyst was mainly characterized by the techniques of X-ray diffraction, transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, H₂ temperature-programmed reduction, NH₃/NO + O₂ temperature-programmed desorption and in situ diffuse reflectance infrared Fourier transform spectroscopy. Both the atomic concentration of Cu⁺ and chemisorbed oxygen species are enhanced by the coating of Fe₂O₃, which facilitates NO attack on active sites, resulting in the in situ formation of NO₂ and promoting the “fast SCR” reaction. Moreover, there is a strong interaction between CuO_x and Fe₂O₃, which could not only lead to better reduction ability but also raise the acid amount and enhance the acid strength as well as NO_x adsorption ability. Based on these favourable properties, the Fe₂O₃@CuO_x catalyst exhibits a higher activity and more extensive operating temperature window than the catalyst without Fe₂O₃. More importantly, the Fe₂O₃ not only prevents the generation of ammonium sulfates from blocking the active sites but also inhibits the formation of copper sulfates, resulting in a high SO₂-tolerance. In addition, the catalyst also displays favourable stability and H₂O resistance. The rational design of 3D hierarchical foam-like Fe₂O₃@CuO_x paves a new way for the development of environmentally-friendly and high-performance monolith deNO_x catalysts.