AbstractBACKGROUNDNon‐value agrifood byproducts are rich in biomolecules such as proteins and polysaccharides, and possess film‐forming ability, motivating their use in the development of biodegradable plastics. This work studied the feasibility of using locust bean milling‐derived dust (LBMD) as a source of biomolecules suitable for developing biodegradable plastics.RESULTSLBMD is composed of 56% protein, 28% carbohydrate, 10% moisture, 6% lipid, and 2% ash. In addition, phenolic compounds are also present. The carbohydrates are mainly composed by (1 → 4)‐mannose, (1 → 4,6)‐mannose, and t‐galactose glycosidic linkages. Depending on the LBMD concentration used, when employed in casting biodegradable plastics, LBMD yields transparent yellowish bioplastics with 90% elongation at break and surface water contact angles ranging from 60° to 90°. Additionally, LBMD‐based bioplastics display antioxidant activity, inhibiting cationic 2,2′‐azino‐bis‐(3‐ethylbenzothiazoline‐6‐sulfonic acid) (ABTS) radicals up to 61% in just 24 h. LBMD‐based bioplastics are disintegrated when incubated on the soil surface for 34 weeks, perhaps acting as a soil nutrient.CONCLUSIONLBMD represents a potential source of biomolecules for producing transparent, flexible, water tolerant, antioxidant, and biodegradable bioplastics, opening up opportunities to implement a novel circular strategy to valorize this locust bean industry byproduct. © 2022 Society of Chemical Industry.