Fully biobased edible films were prepared using native potato starch plasticized with glycerol and further reinforced with catechin (Cat) and starch nanocrystals (SNC) obtained by acidic hydrolysis from waxy maize starch granules. The thermal stability of starch nanocrystals obtained at different pH was studied, resulting on a decreasing in thermal stability at higher pH values. The X-ray diffraction patterns of the plasticized reinforced materials display complete destructuration of starch by solvent casting process. Plasticized films showed lower onset degradation temperatures than non-plasticized starch film. The reduction of the inter- and intra-molecular bonds interaction within the polymer matrix due to glycerol presence leads to a decrease of the thermal stability of the whole system. On the other hand, Cat and SNC produced an increase on the thermal stability of the bionanocomposites delaying the beginning of the thermal decomposition of starch/glycerol systems of about 20 °C. The mechanical performance was also improved in the ternary bionanocomposite edible films. All the edible films were fully disintegrated in compost conditions suggesting their possible applications as biodegradable edible films for packaging.