We report enzymatically degradable, star polypeptides with uniquely sharp and reversible upper critical solution temperature (UCST) behavior in aqueous solutions. UCST transitions of star-poly(L-ornithine-co-L-citrulline) were tunable via degree of uredio modification and/or length of polypeptide arms. Moreover, star polypeptides were assembled into layer-by-layer films with tannic acid and resulting films displayed robust and tunable UCST-triggered swelling transitions.