Dual-atom catalysts (DACs) are expected to improve the catalytic activity compared to single-atom catalysts (SACs). This improvement is attributed to the synergistic interaction between adjacent bimetallic atoms in DACs. Recently, the highly active Fe2N5P sites embedded in covalent organic framework-derived carbon have been demonstrated to catalyze oxygen reduction reaction (doi:10.1021/acscatal.3c02186). Motivated by this fascinating finding of Fe2N5P-based DACs, their potential for catalyzing hydrogen evolution reaction (HER) has been investigated. Thus, electrocatalytic activities of the Fe2N6 and Fe2N5P-based DACs embedded in graphene layer were systematically investigated toward the HER. Our results show that the Fe2N6 site embedded in graphene shows high catalytic activity and selectivity toward the HER. However, our results reveal that the P atom in the Fe2N5P dual-site facilitates the × H formation and thus improves its catalytic activity toward HER due to a greater degree of synergistic effect. The computed Gibbs free energies confirm the higher feasibility of HER on the Fe center of Fe2N5P compared to the Fe2N6 DAC.