Perovskite materials have emerged as highly promising frontier materials for a wide range of optoelectronic applications, including solar cells, light-emitting diodes (LEDs), lasers, and photodetectors (PDs). Taking perovskite-based solar cells (PSCs) as a representative example, these devices demonstrate significant advantages over traditional silicon-based solar cells, such as low costs, high power conversion efficiency (PCE), and exceptional light absorption capabilities. However, residual strain inherent to the fabrication process unavoidably degrades the device performance and consistency. This review comprehensively presents the latest developments in strain regulation techniques at the nanoscale in perovskite materials, first elucidating the concept of residual strain and its intricate relationship with various physicochemical properties. The discussion then delves into the underlying mechanisms of residual strain regulation at the nanoscale. This review discusses specific engineering strategies for residual strain regulation in perovskite-based optoelectronic devices, including solar cells, LEDs, lasers, and PDs. By systematically examining the definition, mechanisms, and methodologies of strain regulation in nanoscale perovskite materials, the review provides a comprehensive framework for understanding its critical role in device performance. Furthermore, this review also identifies and clarifies the key challenges hindering the advancement of high-performance perovskite-based devices, laying a solid foundation for future research directions in this rapidly evolving field.