The energy consumption and carbon emissions of buildings account for 34% and 37% of the global totals, respectively; thus, the development of energy-saving and carbon-neutral technologies in buildings is crucial for addressing the global energy crisis and reducing the carbon footprint. This work demonstrates a novel energy-generating smart window integrating a laminated semitransparent organic photovoltaic (STOPV) and a reversible metal electrodeposition-based electrochromic device (ECD). The smart window in the low-transmittance (tinted) state shows a significant light reflection property, which not only generates similar to 16% more electricity relative to the high-transmission (clear) state but also shows a good heat insulation effect, reducing the temperature by 1.6 degrees C. Building energy simulations demonstrate that the smart window achieves an energy gain (sum of energy saving and energy generation) ranging from 10.1% to 16.2% in different cities around the world, indicating that the reflection-based smart window has great potential in energy-efficient and carbon-neutralized buildings.