Abstract: Nanosized tungsten carbide (WC)/carbon (C) catalyst was synthesized via a novel ultra-rapid confinement combustion synthesis method. The amount of activated carbon (AC) plays an important role in the morphology and structure, controlling both the precursor and final powder. The WC particles synthesized inside the pores of the AC had been 10–20 nm because of the confinement of the pore structure and the large specific surface area of AC. When used for oxygen reduction performance, the half-wave potential was −0.24 V, and the electron transfer number was 3.45, indicating the main reaction process was the transfer of four electrons. The detailed electrocatalytic performance and underlying mechanism were investigated in this work. Our study provides a novel approach for the design of catalysts with new compositions and new structures, which are significant for promoting the commercialization of fuel cells.