Abstract Natural extracts are investigated as plasticizers of starch–glycerol biobased films for food coating applications. For this purpose, films with cassava starch, glycerol, and distilled water with and without green tea or basil extracts are obtained by solvent casting. The plasticizing effect of the extracts is confirmed from the films crystalline structure, thermal degradation behavior, glass transition temperature, and tensile properties. Increased mobility of starch chains is the result of a strong interaction between extract components and starch molecules. The Kohlrausch–Williams–Watts (KWW) theoretical modeling, used for the first time to determine the effect of antioxidant components in starch films, also confirms the plasticizing effect of either green tea or basil extracts. In addition, the original luminosity of the starch film is not compromised by the incorporation of the extracts. Moreover, a delay in the starch retrogradation is achieved, making the film more durable and hence, very promising to be used as food coating.