Waterproof and breathable (W&B) membranes can resist liquid water penetration while transmitting water vapor simultaneously, which is critical for improving the comfort and protection offered by the resulting textiles; however, it remains a substantial challenge to construct promising nontoxic W&B membranes based on green solvents. Here, a simple and scalable strategy is developed for fabricating green, W&B, polyurethane nanofibrous membranes based on an ethanol solvent via emulsion electrospinning and post thermal treatment. A novel ethanol-soluble and spinnable polyurethane is synthesized by a stepwise polymerization reaction. Notably, green nanofibrous membranes with high hydrophobicity are obtained based on fluorinated polyurethane/ethanol emulsions, utilizing the synthesized polyurethane as the template polymer. Furthermore, the introduction of the aziridine crosslinker (tris (2-methyl-1-aziridine propionate) (TTMA)) constructs the structure by post thermal treatment between TTMA and ethanol-soluble polyurethane, resulting in the exceptional ethanol resistance of the nanofibrous membranes. The resulting membranes present integrated functionalities of a robust hydrostatic pressure of 86.2 kPa, high water vapor permeability of 13.1 kg m(-2)d(-1), good air permeability of 5.5 mm s(-1), low mass-loss rate of 8.6 wt% after 60 min ethanol immersion, and desirable elasticity with a strain recovery ratio of 79.2%, offering strong potential for the next generation green and nontoxic protective textiles.