 Tailoring the composition and structure is an effective approach for improving the properties of electrocatalysts in fuel cells. In this study, the core–shell Pd–P@Pt nanoparticles were synthesized using a seed-mediated growth method and applied to the formic acid oxidation reaction like electrocatalysts. The core–shell structure was confirmed by transmission electron microscopy, elemental mapping analyses, energy-dispersive X-ray spectroscopy line scan, inductively coupled plasma mass spectrometry, and X-ray photoelectron spectroscopy. The catalytic activity and durability were evaluated by cyclic voltammetry, electrochemically active surface area loss, and chronoamperometry. The obtained particles exhibit higher catalytic activity and durability compared to those of Pt/C and Pt black commercial reference catalysts due to the synergistic effect between the Pd–P core and the Pt shell. In addition, the Pt shell inhibits the corrosion of Pd in the acidic solution, resulting in good stability.