Bacterial adhesion has become a significant problem in industry and in the domestic domains due to causes loss of capital, labor, and energy worldwide. Microbial resistance to biocides and antimicrobials is a major concern, and several applications have been designed to prevent and inhibit bacterial adhesion. Therefore, there has recently been a demand for materials having antibacterial properties that contain active components which do not cause antibiotic resistance. Among them, integration of essential oils with micro/nano fibers as green and safe antimicrobial compounds was considered to have potential. For this reason, in this study, coatings containing St. John’s wort oil (SJWO) onto porous cellulose acetate ultrathin fiber (pCA_UF) were produced and the antibacterial and antifouling activities were evaluated. The average fiber diameter of 1356.37 ± 496.89 µm and the pore diameters of 413.91 ± 173.52 µm analyzed by scanning electron microscopy (SEM). In addition, the thickness of the coatings was found as 226 ± 35 µm. Attenuated Fourier-transform infrared (ATR-FTIR) indicated a physical type of interaction between SJWO and pCA_UF. Contact angle (CA) results confirmed the presence of SJWO on the pCA_UF decreased the hydrophobicity from 160 ± 16° to 74 ± 2°. pCA_UF-SJWO coatings showed a reduction in adherent bacteria such as Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus, compared to the glass substrate and pCA_UF coatings. Overall, the data supports the use of ultrathin fiber with essential oil coatings for bacterial adhesion.