Simplifying the anchoring process of Ru nanoparticles (NPs) and activating their bifunctional activity are challenges in the construction of Ru-based catalysts. In this work, FeCoP nanosheets anchored by Ru NPs (r-Ru/FeCoP) were innovatively synthesized using an oxygen defect-assisted-gas-phase phosphorization strategy. Surprisingly, the η100 values of r-Ru/FeCoP in the alkaline hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) processes were 0.8 and 0.58 times those of Pt/C and RuO2, respectively. Notably, the rich Ru NPs as HER active sites on r-Ru/FeCoP enhanced the conductivity of the catalyst and promoted the reaction kinetics for HER, while the metal atoms on the FeCoP nanosheets served as OER active sites to accelerate the desorption of O2. The synergy between the two promoted the improvement of overall water splitting efficiency. Overall, this work provides a new approach for the development of low-cost bifunctional catalysts with high Ru utilization.