A vapor deposition method was applied to regulate strain in perovskite thin films, reducing defect formation and limiting nonradiative recombination. The low-strain films extended carrier lifetimes and modified ion migration behavior, enabling vacancy-related degradation to recover naturally in dark conditions through ion redistribution. Devices incorporating these films achieved a power conversion efficiency of 20.2% in inverted architecture and retained 85% of their initial performance after 1,600 hours of continuous operation. The devices also explained consistent stability during repeated light–dark cycling and maintained functionality under long-term ambient exposure. These results exhibits the importance of strain control in improving the durability, efficiency, and self-healing capability of vapor-deposited perovskite solar cells for extended practical use.