Highly active and durable electrocatalysts for the cathodic oxygen reduction reaction (ORR) are vital for the large-scale commercialization of proton exchange membrane fuel cells. Alloying Pt with transition metals is a promising method to enhance the ORR catalytic activity, but the leaching of transition metals is inevitable, which deteriorates the stability. Here, we report the design of a P-doped PtCo electrocatalyst supported on carbon via a facile one-pot hydrothermal method. On the one hand, the introduction of P into the carbon support by phytic acid can enhance the anchoring ability of the PtCo alloy and inhibit the migration of nanoparticles. On the other hand, the doping of P into the lattice of the PtCo alloy further tunes the electronic effect, which improves activity and stability simultaneously. The mass activity of as-prepared P5-PtCo/C at 0.9 V can reach 0.72 A mgPt–1, which is 4.5 times higher than that of commercial Pt/C. After an accelerated durability test (ADT) of 30,000 potential cycles, the mass activity only decreased by 9.4%. Meanwhile, the average particle size of the catalyst slightly increased from 4.94 to 5.15 nm after the ADT of 70,000 potential cycles. This study provides a facile approach for constructing nonmetal-doped PtM catalysts with improved durability for the ORR.