Electronic metal-support interaction (EMSI) plays a crucial role in catalysis as it can induce the electron transfer between metal and support, modulate the electronic state of supported metal, and optimize the reduction of intermediate species. In this work, the tailoring of electronic structure of Pt single atom supported on N-doped mesoporous hollow carbon sphere (Pt₁/NMHCS) via the strong EMSI engineering was reported. The Pt₁/NMHCS composite is much more active and stable than the nanoparticle (Pt_NP) counterpart and commercial 20 wt.% Pt/C for catalyzing the electrocatalytic hydrogen evolution reaction (HER), exhibiting a low overpotential of 40 mV at 10 mA cm⁻² current density, a high mass activity of 2.07 A mg⁻¹_Pt at 50 mV overpotential, a large turnover frequency of 20.18 s⁻¹ at 300 mV overpotential and outstanding durability in acidic electrolyte. Detailed spectroscopic characterizations and theoretical simulations reveal that the strong EMSI effect in a unique N₁−Pt₁−C₂ coordination structure significantly tailors the electronic structure of Pt 5d states, resulting in promoted reduction of adsorbed proton, facilitated H−H coupling and thus Pt-like HER activity. This work provides a constructive route for precisely designing single Pt atom-based robust electrocatalysts with high HER activity and durability.