The film or coating is one of the vital components in food packaging systems; thereby, it is necessary to promote them with potent functions. Nanocomposite films based on carboxymethyl cellulose (CMC) containing Al2O3@SiO2 and Al2O3@TiO2 nanoparticles were obtained by casting techniques. The synthesized materials were characterized by their morphology, size, and structure. Moisture absorption (MA), water vapor permeability (WVP), and gas transmission rate (GTR) were also measured to study the barrier properties of films. According to the results, the core-shell nanoparticles showed a smaller diameter, uniform dispersion, and no accumulation in the film matrix compared to the alumina allotropes (γ-,η-,α-Al2O3). The presence of Al2O3@SiO2 and Al2O3@TiO2 nanoparticles significantly regulated MA, WVP, and GTR compared to the allotropes. The most significant reduction in MA, WVP, and GTR belonged to the γ-Al2O3@SiO2 (2.11%), η-Al2O3@TiO2 (6.09 × 10−10 g/m s pa), and η-Al2O3@TiO2 (0.21 cm3/m2d bar) respectively. To sum up, embedding core-shell nanoparticles within the matrix of polymeric films (CMC) can be a good idea to increase the efficacy of food packaging systems.