By performing first-principles calculations, CO oxidation catalyzed by Fe-embedded defective α-graphyne was systematically investigated. It was found that Fe atoms were strongly anchored at the sp-C vacancy site of α-graphyne with a large binding energy of -5.28 eV and effectively adsorbed and activated O2 molecules. Then, we systematically compared CO oxidation by activated O2via Langmuir-Hinshelwood (LH) and Eley-Rideal (ER) mechanisms. The calculated potential energy surfaces show that the Fe-doped α-graphyne can efficiently oxidize CO via the ER mechanism, in which the threshold of the rate determining step is 0.77 eV. Furthermore, Fe doping shows little effect on the diffusivities of CO, O2, and CO2, which can further enhance its catalytic performance.