MXene, a family of two-dimensional (2D) transition metal carbides and nitrides, has intriguing electrochemical energy storage and electrocatalysis applications. Introducing the electronic metal–support interaction (EMSI) effect is one effective strategy to optimize the catalytic efficiency for MXene-based composites. However, most of the studies concentrate on optimizing the performance of metals rather than supported substrates by using this strategy. In this work, we mainly investigate the influence of an EMSI effect on the performance of the supported substrate (Ti₃C₂T_x MXene). Detailed scanning electrochemical microscopy and numerical simulations results reveal that the charge distribution on the Ti₃C₂T_x basal plane (approximate 100 nm-radius) surrounding Au nanoparticles (20 nm-radius) was significantly enhanced as a result of –O being the majority surface functional group on Ti₃C₂T_x that was attached to Au nanoparticle, and the related hydrogen evolution reaction (HER) activity was much better than that of the unaffected Ti₃C₂T_x basal plane, which even can be comparable to that of Au. This finding will be helpful for designing new strategies to enhance the overall catalytic performance of various MXene-based composites.