Abstract: Chilled mutton is highly nutritious but prone to spoilage during storage due to microbial contamination and lipid oxidation. A high-barrier packaging film for chilled mutton was developed in this study. A flexible graphene oxide (GO)-grafted poly (L-lactic-co-butanediol itaconate) (GO-g-PLBI) was synthesized by melt polycondensation. GO-g-PLBI was blended with PLLA pellets to form PGLBI film. A high-barrier PGLBI/GO-carboxymethyl cellulose (CMC) composite film was subsequently fabricated by depositing a GO-CMC layer onto the PGLBI surface via vacuum filtration. The packaging properties of the composite film, such as gas barrier performance and its application potential in non-contact packaging of chilled mutton were investigated. Results demonstrated that incorporation of GO effectively improved the hydrophilicity of PGLBI, facilitating its composite with the GO-CMC component. Characterizations by Scanning Electron Microscopy and X-Ray Diffraction confirmed that a dense "brick-and-mortar" structure was formed inside the PGLBI/GO-CMC film, which achieved an exceptionally low oxygen transmission rate of 0.5 cm³/m²·d. Additionally, the composite film exhibited excellent ultraviolet shielding performance, with transmittances of 1.45% for long-wave UV and 7.03% for medium-wave UV. When applied to chilled mutton packaging, the composite film could inhibit microbial proliferation, protein degradation, and lipid oxidation during storage. Compared with the commercial high-barrier polyamide/polyethylene film, the PGLBI/GO-CMC film extended the shelf life of chilled mutton by 5 days.