The limited use of xanthan (Xa) and carboxymethyl cellulose (CMC) in the food packaging industry is due to their poor barrier and antimicrobial properties. The objective of this work was to enhance the characteristics of the CMC/Xa composite coating by incorporating ZnO nanoparticles (ZnO-NPs) that were prepared through a green method through Coriandrum sativum extract. FTIR and XRD confirmed the successful preparation of the coating and verified the interactions between its components. Compared to the neat CMC/Xa system, systems incorporated with ZnO-NPs exhibited excellent water barrier, mechanical, thermal, and antimicrobial characteristics. The CMC/Xa/ZnO-NP systems effectively prolonged the shelf life of tomatoes for a storage period of 20 days without any significant indications of spoilage or mass loss of the coated tomatoes. The obtained results indicated that the developed coating has the potential to replace traditional plastic packaging and effectively preserve food products.