Abstract: Polymer materials are often vulnerable to UV-induced photodegradation and yellowing, which can significantly degrade their performance. Therefore, developing intrinsically UV-shielding polymers is essential. This study leverages sulfur’s unique electronic structure to synthesize hydroxyl-terminated sulfur-containing prepolymers through proton-transfer anionic hybrid copolymerization. This process involves the use of 1,4-butanediol diacrylate （BDDA）, 1,3-dioxolan-2-one （TMC）, and elemental sulfur （S₈）. The cyclic monomer TMC plays a crucial role in regulating the reaction, effectively suppressing excessive crosslinking while facilitating decrosslinking. Following this, the prepolymers are cured with toluene diisocyanate （TDI）, resulting in novel sulfur-incorporated polyurethanes. The resulting products demonstrate the ability to provide full-band UV shielding, exhibiting near-zero transmittance in the UV region and over 80% transmittance in the visible spectrum. Furthermore, these polymers display remarkable thermal stability, with an initial decomposition temperature exceeding 224 ℃. Their mechanical properties are tunable, achieving tensile strengths of up to 7.2 MPa, and they feature outstanding reprocessability due to the presence of dynamic polysulfide bonds. Additionally, the materials show significant degradability, which aligns with the increasing demand for sustainable solutions. This work offers a straightforward strategy for fabricating high-performance intrinsically UV-shielding polymers, presenting broad application potential in UV-protective films, eco-friendly packaging, and outdoor coatings.