Two-electron oxygen reduction reaction (ORR) catalysts are essential for the electrosynthesis of hydrogen peroxide (H₂O₂). MXenes, a rising family of two-dimensional (2D) transition metal carbides, have been extensively studied for energy storage and (photo)electrocatalysis due to their rich chemical compositions and tunable electronic structures. In this work, three representative MXenes of Ti₃C₂T_x, V₂CT_x, and Nb₂CT_x were selected for H₂O₂ electrosynthesis and we found that MXenes are inherent two-electron ORR catalysts with high H₂O₂ selectivity. In addition, this work critically evaluates their electrocatalytic activity and stability. Interestingly, Nb₂CT_x catalyst maintains better electrocatalytic activity and higher stability for a long time test, although the stability of Ti₃C₂T_x and V₂CT_x catalysts is poor owing to the metal dissolution property of Ti and V in alkaline media. Moreover, the assembled device based on Nb₂CT_x catalyst presents a high H₂O₂ production and a rapid organic dye decoloration ability.