This study aimed to determine the main physical properties of green synthesized ZnO nanoparticles (ZnO-NPs) using Thymus syriacus plant extract and their antibacterial activities against eight different Gram-positive and Gram-negative plant bacterial disease agents. The surface morphological, structural, optical and electrical attributes of the ZnO films were analyzed by various types of characterization techniques. The authors have observed that the microstructural and surface morphological properties considerably changed by using T. syriacus plant extract. UV–Vis. analysis showed that the bandgap values are increased from 3.17 to 3.28 eV with the T. syriacus content in the growth solution. Impedance measurements presented an increase of the semicircle diameters with the increase % of T. syriacus. The antibacterial effectiveness of ZnO-NPs was evaluated against plant pathogenic bacterial species by using the agar disc diffusion method. Established on inhibition zone diameter values, ZnO-NPs displayed varying levels of antibacterial activities against all bacterial species tested. Gram-positive bacterial species were found more sensitive than Gram-negative species. In comparison, the highest antibacterial activity was displayed against Clavibacter michiganensis subsp. michiganensis and Bacillus subtilis subsp. subtilis, the lowest antibacterial activity was recorded for Pseudomonas corrugata. The present research findings suggest that the green synthesized ZnO-NPs have a prospective to be used as optoelectronic materials and antibacterial agents against plant pathogenic bacterial disease.