This work explores the antifungal effect of Zataria multiflora essential oil (ZEO) and its nanocapsules (ZEO-NCs) on the culture medium and UF-Feta cheese. After selecting ZEO among the three desired EOs (based on MIC and MFC assays), chitosan nanoparticles were prepared in optimal conditions. Based on GC-MS analysis, the main constituents of ZEO were thymol (20.09%) followed by cymene (19.88%), and gamma-terpinene (18.58%). According to the response surface method, the optimum amounts of chitosan, tween 80, and ZEO were 7.97% w/v, 1.3% v/v, and 0.87% v/v, respectively, to produce the proper nanoparticles with the minimum particle size and the maximum values of zeta potential and encapsulation efficiency. A sharp peak at 2θ of 20◦ in the XRD spectrum of chitosan and its broadening in the spectrum of ZEO-NCs exhibited a high degree of crystallinity and entrapment of ZEO within nanocapsules. Also, the SEM images showed clusters of accumulated particles with relatively spherical nano-sized capsules. The formulated nanocapsules showed a stronger antifungal effect on Penicillium citrinum and Aspergillus niger, while the free form of ZEO caused more inhibition of Aspergillus flavus. Also, the lowest Antifungal activity among all treatments was recorded for Non-loaded NCs. پرونده مقاله