Developing new methodology of polypeptide synthesis has afforded well-defined polymer-polypeptide hybrid materials for various bio-applications. One of the most efficient routes is a ring-opening polymerization of α-amino acid N-carboxyanhydrides （NCAs）, permitting the preparation of well-defined structures in terms of the molecular weight and terminal structures of the polypeptide. However, highly toxic phosgene derivatives are usually required for the synthesis of NCAs, and the susceptive nature of NCAs to moisture and heating are major obstacles for its practical and industrial-scale use. In this work, we demonstrate a phosgene-free synthesis of polypeptide by polycondensation of N-aryloxycarbonyl α-amino acids, where these activated urethane derivatives gives directly corresponding polypeptides by forming NCAs in situ and the polymerization with the elimination of phenol and CO2. Due to the ease of handling and the simple procedure, this methodology for making a functionalized polypeptide is more useful and valuable than the conventional ring-opening polymerization of NCAs, and expected to be applied to designing the biocompatible and biodegradable biomaterials.