A Cr/CoNiCrAlTaY bilayer coating was prepared on the Ti-45Al-8.5Nb alloy by plasma surface metallurgy technique. The as-prepared coating with a grain size of ~2 μm exhibited a dense microstructure and strong adhesion due to metallurgical bonding, consisting of outermost Cr layer and CoNiCrAlTaY transition layer. The typical power-law relationship between mass gain and time was obtained for the coated specimens with a rate exponent of 3.18 following oxidation at 1173 K. The top Cr₂O₃ film and spinel oxides (i.e., NiCr₂O₄ and CoCr₂O₄) exhibited a protective effect with a low oxidation reaction rate. Interfacial analysis identified Ta precipitates (Cr₂Ta and TaAl₃) and Ta oxides (Ta₂O₅ and Ta₂O₃), which played an essential role in retarding rapid diffusion and enhancing adhesion and oxidation resistance.