Designing highly active, low-cost, and bifunctional oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) catalysts is urgent for the development of metal–air batteries. Herein, by density functional theory (DFT) calculations, we systematically reported a series of dual-metal atom adsorbed novel two-dimensional (2D) MBenes as efficient bifunctional catalysts for the OER/ORR (namely 2TM/TM₁TM₂–Mo₂B₂O₂, TM = Mn, Fe, Co, Ni). Our theoretical results show that 2Ni–Mo₂B₂O₂, FeCo–Mo₂B₂O₂ and CoNi–Mo₂B₂O₂ exhibit outstanding OER/ORR catalytic activity with overpotentials of 0.49/0.27 V, 0.38/0.50 V and 0.25/0.51 V, respectively, exceeding those of IrO₂(110) for the OER and Pt(111) for the ORR. Additionally, these highly active bifunctional catalysts can effectively suppress the hydrogen evolution reaction (HER), ensuring the absolute preference for the OER/ORR. More importantly, the Bader charge (Q_TM) of adsorbed dual-metal atoms is used as a descriptor of OER/ORR catalytic activity, which is linearly related to η^ORR and volcanically related to −η^OER. Our work not only provides new theoretical guidance for developing noble metal-free bifunctional electrocatalysts but also enriches the application of MBenes in electrocatalysis.