Developing new methods to encapsulate fragile active compounds into packaging films is important for extending the shelf life of foods. In this study, the gelatin/fiber bilayer packaging film was fabricated by depositing carvacrol‐loaded core–shell zein/polyvinyl pyrrolidone fibers on gelatin film. The tensile strength, elongation, oxygen transmission rate, and water vapor permeability of the gelatin/fiber film were 5.95 MPa, 56.63%, 63.27 ml/m2 d, 0.1 MPa, and 7.416 g·mm/m2 h kPa, respectively. The gelatin/fiber film was applied to sea bass fillet preservation. At day 8, the total viable count and thiobarbituric acid of the sea bass fillets treated with gelatin/fiber film were 8.12 log CFU/g and 0.73 mg MDA/kg, which were lower than that of the control group. Moreover, the gelatin/fiber film treatment showed the effect of delaying fish color change and pH increase, and prolonged the shelf life of sea bass fillets by 2–4 days. Novelty impact statement: Gelatin film deposited with carvacrol‐loaded core–shell fibers was prepared. Shelf life of Japanese sea bass fillets was extended by the gelatin/fiber film. The active bilayer film showed high antimicrobial and antioxidant activities. [ABSTRACT FROM AUTHOR]