Bi?Pt?O? pyrochlore is thought to be one of the most promising oxide catalysts for application in fuel cell technology. Unfortunately, direct film growth of Bi?Pt?O? has not yet been achieved, owing to the difficulty of oxidizing platinum metal in the precursor material to Pt??. In this work, in order to induce oxidation of the platinum, we annealed pulsed laser deposited films consisting of epitaxial ??Bi?O? and co-deposited, comparatively disordered platinum. We present synchrotron x-ray diffraction results that show the nonuniform annealed films contain the first epitaxial crystals of Bi?Pt?O?. We also visualized the pyrochlore structure by scanning transmission electron microscopy, and observed ordered cation vacancies in the epitaxial crystals formed in a bismuth-rich film but not in those formed in a platinum-rich film. The similarity between the ??Bi?O? and Bi?Pt?O? structures appears to facilitate the pyrochlore formation. These results provide the only route to date for the formation of epitaxial Bi?Pt?O?.