Thermochromic perovskite smart windows that have recently emerged can dynamically and passively change the solar transmittance as the ambient temperature changes, giving them the potential to contribute to energy saving in buildings. However, thermochromic perovskites can be easily damaged by water and moisture in the ambient air. To solve this problem, in this study, a durability-enhanced thermochromic perovskite smart window is proposed. By integrating an inorganic buffer layer and a hydrophobic nano-silica coating, the new thermochromic perovskite window demonstrates superhydrophobicity with a contact angle of 160° to repel water. And it can maintain a high solar modulation ability (Δτsol > 20%) after a 45-day durability test in an ambient environment with ∼60% relative humidity, representing ∼20 times the lifespan of an unprotected thermochromic perovskite window. This new window also demonstrates an excellent optical performance with a high luminous transmittance of ∼83% in a transparent state, a high solar modulation ability (Δτsol) of ∼24%, and a low haze of ∼30%. Overall, the proposed novel window structure provides an easy and effective strategy to improve the lifespan of thermochromic perovskite, further paving the way for practical applications in energy-efficient smart windows.