<p>Photosensors for aerospace and deep-space exploration require tolerance to high radiation levels and extreme temperatures. However, prolonged exposure to high-energy particles and severe thermal cycling inevitably induces material degradation. While van der Waals crystals possess inherent structural robustness and hold promise for such harsh environments, they still suffer from interfacial defects and operational instability that limit practical applications. Here we report a heteroatom-intercalation approach for two-dimensional wide-bandgap oxides potassium niobate (KNb₃O₈, KNO) that concurrently passivates structural defects and induces interface polarization as well as band structure reconstruction, which thus significantly improves the photodetection performance and enables solar-blind imaging applications. The resulting devices achieve stable operation over a broad temperature range of −263.15 ^oC to 300 ^oC and robust radiation tolerance up to 200 kGy at a dose rate of 6 Gy/s, outperforming most existing systems. This intercalation strategy provides a promising pathway for the rational design of harsh-environment-resistant optoelectronics.</p>