Carbon-based single-atom catalysts (SACs) have shown promising applications in the conversion of CO₂ into CO. However, the deep reduction process for the production of high-value hydrocarbons is largely limited due to the weak activation of CO. Herein, on the basis of first-principles calculations, a simple coordination regulation method of the active site is proposed to improve the conversion of CO₂. Taking NiN₄ as an example, by introducing heteroatoms (B, C, O, P, and S atoms), we reveal that NiN₃B can effectively capture *CO and further convert to CH₄ with an ultralow limiting potential of −0.42 V. The excellent catalytic performance is probably attributed to the formed synergistic dual active sites between non-metal B and metal Ni atoms. Moreover, NiN₃B can maintain good stability and the catalytic performance can be further enhanced by increasing the B-doping concentration. This work demonstrates that coordination regulation is an effective strategy to improve the performance of single-atom catalysts and paves a possible way to advance the development of non-Cu-based CO₂RR electrocatalysts for high-value hydrocarbon products.