Improved activity and stability Pt-based catalysts for the oxygen reduction reaction (ORR) are needed to perpetuate the deployment of polymer electrolyte fuel cells (PEFCs) in the transportation sector. Here, we use atomic layer deposition of TiO2 and Pt coupled with thermal reductive annealing to prepare Pt3Ti electrocatalysts. The atomic level synthetic control resulted in Pt3Ti nanoparticles with high ORR performance, including a mass activity of 1.84 A/mgPt and excellent electrochemical stability. The Pt3Ti nanoparticles show excellent specific activity — 5.3-fold higher than commercial Pt/C and 3-fold higher than polycrystalline Pt, exceeding the performance of any PtTi catalysts reported to date. Combined experimental and computational efforts indicate that Pt enrichment on the Pt3Ti enhances the activity, and the intrinsic stability of the Pt3Ti phase provides durability. This knowledge, along with the facile fabrication of alloys by atomic layer deposition, can be leveraged to designed improved performance catalysts.