The work aims to investigate the effects of oregano essential oil (OEO) on the physicochemical properties and functional properties of polyvinyl alcohol (PVA) and chitosan (CS) composite films. Composite films were prepared by casting with PVA and CS as film-forming substrates and OEO as an active ingredient. The physical properties, oxidation resistance, and antibacterial properties of PVA/CS composite films containing OEO were determined, and the films were used for chicken preservation. The results showed that the addition of OEO significantly increased the thickness, moisture content, water contact angle, tensile strength, and elongation at break of the composite films, while reduced the water vapor permeability of the composite films. Moreover, the addition of OEO significantly enhanced the antioxidant and antibacterial capabilities of the composite films. Specifically, the PVA/CS-OEO4 films demonstrated a remarkable DPPH radical scavenging efficiency of up to 73.80% and effectively inhibited the growth of Escherichia coli and Staphylococcus aureus. Compared with the control group, wrapping chicken at 4 ℃ with PVA/CS-OEO films could significantly inhibit the growth of microorganisms and lipid oxidation, and effectively delayed the changes of pH and sensory properties of chicken during refrigerated storage. Among which, PVA/CS-OEO4 had the most apparent effect. The addition of OEO can improve the mechanical properties, water vapor barrier, antioxidative and antibacterial properties of PVA/CS films. PVA/CS-OEO4 could be a promising material as packaging films for extending the shelf life of chicken to 10 days at 4 ℃.