This study focused on the development of antioxidant biodegradable films based on PLA reinforced with an organically modified montmorillonite [Dellite 43B (D43B)] and a natural additive (thymol) to obtain nano-biocomposites based on renewable resources with antioxidant activity and enhanced properties for active packaging applications. A full characterization was carried out including the determination of thermal, structural, mechanical and functional properties. Finally, the presence of thymol in the nano-biocomposites was determined by HPLC-UV analysis and antioxidant activity assessed by using the DPPH method.