Single-crystal films are at the foundation of a number of advanced technologies, such as for devices related to microelectronics, optoelectronics, spintronics, and superconducting electronics. In this study, high-temperature annealing was used to rehabilitate the MgO(001) surface to improve the crystallinity of highly epitaxial LaBaCo2O5+δ (LBCO) films, which have demonstrated potential for applications in fast gas sensors. In comparison with the LBCO film grown on the as-received substrate, solid evidence is presented to support that the rehabbed substrates facilitate deposition of single-crystal LBCO films by radio frequency magnetron sputtering at the optimized conditions. Thus, substrate annealing is demonstrated to be a practical and effective method for rehabbing the damaged surface of a substrate induced by manufacture and surface milling and is promising for a range of important applications based on the growth of single-crystal films.