Abstract: To investigate the protective effect of antioxidant coatings on the storage quality of frozen cut beef, this study employed a polyethylene (PE) film-treated group as the control, and evaluated three coating formulations: 2% sodium carboxymethyl cellulose (CMC-Na) alone, 2% CMC-Na combined with 0.01% tea polyphenols (TP), and 2% CMC-Na supplemented with 0.01% TP and 0.02% vitamin C (Vc). The impacts of these treatments on oxidation stability, protein functional properties, and gel quality of frozen beef during 180 days of cryopreservation were systematically analyzed. The results demonstrated that all three coating treatments significantly suppressed the elevation of thiobarbituric acid reactive substances (TBARS) values and carbonyl content, while mitigating the reduction in total thiol content in beef. After 180 days of freezing, the PE group exhibited increases of 48.50% and 77.83% in TBARS values and carbonyl values, respectively, along with a 61.70% decrease in total thiol content. In contrast, the three coating-treated groups showed sequential increases in TBARS values (39.42%, 39.08%, 39.49%) and carbonyl values (71.43%, 65.49%, 64.79%), as well as progressive decreases in total thiol content (47.92%, 44.81%, 42.99%). Compared with the PE group and the single 2% CMC-Na group, the composite coating groups incorporated with TP and Vc were more effective in alleviating lipid oxidation, minimizing protein carbonylation damage, and retarding total thiol loss in beef during cryopreservation. With respect to protein structure, coating treatments stabilized the α-helix and β-sheet contents of beef proteins, reduced the loss of ionic bonds and hydrogen bonds, inhibited abnormal changes in hydrophobic bonds and disulfide bonds, and delayed the decline in protein solubility and the increase in surface hydrophobicity—among which the Vc-containing composite coating group showed remarkable performance in maintaining the stability of protein secondary structure. Regarding gel quality, coating treatments effectively inhibited the decreases in gel strength, hardness, and chewiness of beef. Notably, the Vc composite coating group displayed superior efficacy in preserving gel strength and texture properties during the late stage of cryopreservation. In conclusion, the antioxidant coating formulated by compounding 2% CMC-Na with 0.01% TP and 0.02% Vc can comprehensively enhance the storage quality of frozen cut beef across multiple dimensions (oxidation stability, protein functional properties, and gel quality), thereby providing theoretical basis and technical support for the long-term preservation of frozen meat in industrial production.