This study explored the synergistic potential of periodate-oxidized cellulose nanocrystals (CNCs) decorated with silver nanoparticles (AgNPs) to enhance the antimicrobial and mechanical properties of poly(vinyl alcohol) (PVA) and poly(l-lactic acid) (PLLA) biopolymer matrices. A concentration-dependent antibacterial activity was demonstrated against both Gram+ and Gram- bacteria, highlighting the potential of CNCs-AgNPs in inhibiting pathogenic strains. Moreover, the tensile strength of PVA and PLLA films was notably improved by incorporating CNCs-AgNPs. The filler demonstrated significant inhibitory effects on bacterial growth in chicken meat samples wrapped in PVA/CNCs-AgNPs nanocomposite films, allowing for an extension of the meat shelf life beyond acceptable microbiological limits. These results highlight the versatile capabilities of CNCs-AgNPs in polymer nanocomposites, positioning them as potent agents for antimicrobial packaging and as contenders for sustainable and functional nanomaterials in various applications.