Verticillium wilt, caused by Verticillium dahliae Kleb., is one of the most important diseases of peppers. Harpin is a bio-activator that may be used as an alternative control against insects and fungi. Therefore, the aim of this study was to describe how harpin affected plants that had been inoculated with V. dahliae. Disease severity in harpin+V. dahliae-treated plants was lowered by a rate of 85.5% compared with V. dahliae plants. In the absence of harpin, V. dahliae caused a reduction in the number of leaves per plant and plant height. Values obtained from leaf dry weight and root dry weight parameters in the plants subjected to harpin+V. dahliae were higher than those exposed to just V. dahliae. Leaf chlorophyll values declined significantly in the plants subjected to V. dahliae, and the total chlorophyll results were Supported by color values. At the end of the study, spraying pepper plants with harpin during the growth period appeared to be a promising strategy to increase plant resistance and protection against V. dahliae.