A mask-inspired thermochromic perovskite smart window (MTPW) has been developed to address the challenges of humidity-induced degradation and poor optical performance in traditional thermochromic perovskite windows (TPWs). Inspired by the trilayer structure of medical masks, the MTPW consists of a T-Perovskite layer, a middle protection buffer layer, and a top superhydrophobic layer. This design enables sufficient water vapor transmission to trigger thermochromism while effectively repelling detrimental water and moisture, thereby extending the lifespan of the window. The MTPW demonstrates superhydrophobicity and maintains a solar modulation ability above 20% during a 45-day aging test, with a decay rate 37 times lower than that of a pristine TPW. It can also immobilize lead ions and significantly reduce lead leakage by 66 times. Furthermore, a significant haze reduction from 90% to 30% is achieved, overcoming the blurriness problem of TPWs. The MTPW's improved optical performance, extended lifespan, suppressed lead leakage, and facile fabrication make it a promising material for green building technologies. The MTPW is fabricated using a solution-based process, involving the spin-coating of a T-Perovskite precursor, followed by the application of a perhydropolysilazane (PHPS) buffer layer and a superhydrophobic SiO₂ nanoparticle layer. The PHPS layer provides protection against water vapor and enhances optical performance, while the SiO₂ layer ensures superhydrophobicity and water repellency. The MTPW exhibits excellent optical performance, with a luminous transmittance of 83.4% in the cold state and 30.4% in the hot state, and a solar modulation ability of 24.4%. The MTPW also demonstrates a low transition temperature (Tc < 45°C) and short transition time (<5 min), making it suitable for practical applications. The MTPW's durability is significantly enhanced, with a 37 times lower decay rate compared to TPWs. Additionally, the MTPW effectively reduces lead leakage by immobilizing lead ions, making it more eco-friendly. The MTPW's flexibility and scalability enable its integration into existing glass windows, making it a promising solution for energy-efficient buildings. EnergyPlus modeling confirms that the MTPW can lead to significant all-year energy savings, making it a valuable material for sustainable building technologies.A mask-inspired thermochromic perovskite smart window (MTPW) has been developed to address the challenges of humidity-induced degradation and poor optical performance in traditional thermochromic perovskite windows (TPWs). Inspired by the trilayer structure of medical masks, the MTPW consists of a T-Perovskite layer, a middle protection buffer layer, and a top superhydrophobic layer. This design enables sufficient water vapor transmission to trigger thermochromism while effectively repelling detrimental water and moisture, thereby extending the lifespan of the window. The MTPW demonstrates superhydrophobicity and maintains a solar modulation ability above 20% during a 45-day aging test, with a decay rate 37 times lower than that of a pristine TPW. It can also immobilize lead ions and significantly reduce lead leakage by 66 times. Furthermore, a significant haze reduction from 90% to 30% is achieved, overcoming the blurriness problem of TPWs. The MTPW's improved optical performance, extended lifespan, suppressed lead leakage, and facile fabrication make it a promising material for green building technologies. The MTPW is fabricated using a solution-based process, involving the spin-coating of a T-Perovskite precursor, followed by the application of a perhydropolysilazane (PHPS) buffer layer and a superhydrophobic SiO₂ nanoparticle layer. The PHPS layer provides protection against water vapor and enhances optical performance, while the SiO₂ layer ensures superhydrophobicity and water repellency. The MTPW exhibits excellent optical performance, with a luminous transmittance of 83.4% in the cold state and 30.4% in the hot state, and a solar modulation ability of 24.4%. The MTPW also demonstrates a low transition temperature (Tc < 45°C) and short transition time (<5 min), making it suitable for practical applications. The MTPW's durability is significantly enhanced, with a 37 times lower decay rate compared to TPWs. Additionally, the MTPW effectively reduces lead leakage by immobilizing lead ions, making it more eco-friendly. The MTPW's flexibility and scalability enable its integration into existing glass windows, making it a promising solution for energy-efficient buildings. EnergyPlus modeling confirms that the MTPW can lead to significant all-year energy savings, making it a valuable material for sustainable building technologies.