Exploiting inexpensive and effective nickel-based catalysts that produce hydrogen from liquid organic hydrogen carriers (LOHCs) is crucial to alleviating the global energy and environmental crisis. In this study, we report a rational strategy that can realize atomically dispersed Ni atoms anchored on vacancy-abundant boron nitride nanosheets (Ni₁/h-BNNS) with high specific surface area (up to 622 m²·g⁻¹) and abundant hydroxyl groups for high efficient hydrogen production. Methanol dehydrogenation results show an excellent hydrogen production performance catalyzed by this Ni₁/h-BNNS, as evidenced by a remarkably high H₂ yield rate (1684.23 mol·mol_Ni⁻¹·h⁻¹), nearly 100% selectivity toward hydrogen and CO, and high anti-coking performance. Density functional theory (DFT) calculations reveal that the outstanding catalytic performance of Ni₁/h-BNNS primarily originates from the unique coordinated environment of atomically dispersed Ni (Ni-B₂O₂) and the synergistic interaction between Ni single atoms and the h-BNNS support. Specifically, the coordinated O atoms play a decisive role in promoting the activity of Ni, and the neighboring B sites significantly decrease the energy barriers for the adsorption of key intermediates of methanol dehydrogenation. This study offers a novel strategy for developing high-performance and stable single-atom Ni catalysts by precisely controlling single-atom sites on h-BN support for sustainable hydrogen production.