Structural materials serving in extreme environments, such as offshore and desert, face persistent threats from impact damage and corrosion. While polyurethane (PU) coatings are widely used for protection (e.g., on wind turbine blades), their effectiveness is often limited by insufficient hardness, impact resistance, and long-term corrosion performance. Inspired by the damage-tolerant architectures of natural sponge and nacre, a bioinspired lamellar coating via alternating spray deposition and UV curing of rigid alumina/PU nanocomposite layers and soft polyurethane acrylate layers is developed. This approach enables conformal, large-area application on complex geometries while featuring rapid preparation and overcoming scalability barriers. Compared to conventional PU coatings, the bioinspired film exhibits a 137% increase in flexural modulus, a 119% enhancement in penetration energy absorption, and a 17% reduction in penetration displacement under dynamic impact. Crucially, it maintains robust corrosion resistance post-impact—microcracks are contained within individual layers, preventing catastrophic failure and electrolyte ingress, much like nacre's protective function in marine settings. Multiscale characterization and finite element analysis confirm that coordinated crack deflection and microcrack networks synergistically mitigate impact stress and preserve electrochemical barrier integrity. This spray-based, UV-cured platform offers a scalable route to multifunctional bioinspired coatings for demanding engineering applications.