The rational design of platinum-based electrocatalysts with optimized metal-support electronic interactions remains a fundamental challenge in achieving atom-efficient hydrogen evolution reaction (HER). This study demonstrates a coordination-driven synthesis strategy to engineer highly dispersed ultra-small α-MoC_1−x anchored on nitrogen-doped carbon (NC) frameworks, leveraging the unique metal-organic coordination chemistry between molybdenum species and imidazolate ligands in ZIF-8 precursors. Through precise control of the carbide crystallization process, we establish an atomic-level interface configuration that enables the preferential anchoring of Pt atoms onto the metastable α-MoC_1−x phase. The resulting strong metal-support interaction (SMSI) induces significant electron redistribution at the Pt/α-MoC_1−x interface, as evidenced by X-ray absorption spectroscopy (XAS). The optimized Pt/α-MoC_1−x/NC architecture demonstrates exceptional HER performance with low overpotentials of 19 and 84 mV at current density of 10 and 100 mA·cm⁻². Remarkably, it achieves a mass activity of 15.3 A·mg_Pt⁻¹ at 100 mV overpotential, 10.9-fold enhancement compared to commercial 20% Pt/C (1.4 A·mg_Pt⁻¹). This work establishes a new paradigm for constructing interfacial electronic environments through support dispersion engineering, providing fundamental insights into the design principles of high-efficiency catalysts for sustainable hydrogen production.