Doped nanomaterials show extremely high atom efficiency, low cost, high stability and activity for CO oxidation, bridging the gap between homogeneous and heterogeneous catalysis. The catalytic mechanism of CO oxidation on three‐silicon‐doped h‐BN is reported. The adsorption of O2 is more advantageous than CO. The electron transfer from the dopant activates the adsorbed O2 and initiates the following CO oxidation. The oxidation process includes O2 adsorption, electron transfer, CO adsorption, oxygen transfer, and CO2 desorption. The energy barriers for the generation of two CO2 molecules in N vacancy dopant are 0.50 and 0.33 eV, respectively. The enhanced catalytic performance indicates that three‐silicon‐doped h‐BN has potential applications to fabricate low cost and high activity BN‐based metal‐free catalysts.