This study introduces an innovative carboxymethyl cellulose (CMC)-based edible nanocomposite coating, with two-dimensional layered double hydroxide nanosheets (2D LDH-NSs) and shellac, engineered to address challenges in fruit preservation. The synergistic integration of shellac and LDH-NS into the CMC matrix is strategically designed with tunable functionalities, encompassing wettability, gas barrier, and tensile properties. Our findings reveal that incorporating shellac and LDH-NS significantly improves the coating's wettability on the mandarin fruit surface, thus bolstering its adherence and uniformity, alongside enhancing its water vapor barrier efficacy and influencing the oxygen permeability. The application of this novel edible nanocomposite coating on Satsuma mandarin (Citrus unshiu Marc.) fruits has yielded promising outcomes in prolonging postharvest shelf life while preserving essential quality attributes, including peel surface morphology, weight loss, hardness, color retention, and nutritional values. Our work signifies a significant leap forward for the edible coating technology and bolsters the postharvest preservation of perishable fruits.