We report on a rapid, single-step method to produce large-area superhydrophobic surfaces via acetone-induced phase transformation of polycarbonate. Crystallization of the polymer leads to the formation of a hierarchical structure composed of microporous spherulites covered with nano-fibrils, and resulted in superhydrophobic wetting behavior. A systematic study of the dependence of surface morphology on the acetone treatment time was conducted to optimize the treatment time and to elucidate the structure formation mechanism. The resulting surfaces exhibit high contact angles, low contact angle hysteresis, and complete dewetting during droplet impact. Theoretical analysis of the wetting and anti-wetting pressures shows that the nano-scale morphology is critical for achieving droplet impact resistance. This simple phase transformation approach could be more broadly applied to other solvent–polymer systems for fabricating large-area hierarchical surface textures.