Verticillium wilt is a very challenging disease occurring on a wide host range. The control of this disease relies on an integrated management approach in which biocontrol products play a crucial role. The aim of this study was to assess the effect of essential oils from thyme and oregano in reducing the severity of Verticillium wilt on tomato and olive and explore their ability to stimulate the activation of resistance mechanisms in the plant. Furthermore, essential oils were evaluated for their capacity to reduce the viability and the germination of V. dahliae microsclerotia. The results showed a positive effect of thyme and oregano in reducing disease severity in tomato by 35% and 40% respectively, and in olive by 43% and 57% for oregano and thyme respectively. Essential oils treatments increased the expression level of PAL in tomato and both PAL and CHS in olive before the inoculation with V. dahliae. However, after the inoculation with the pathogen, the results were not consistent although they reflected a positive trend in promoting plant’s resistance mechanisms. In vitro experiments revealed that essential oils significantly reduced the inoculum density of microsclerotia in the soil 1 year after the treatment. Nevertheless, the direct interaction occurring between essential oil’s active compounds and microsclerotia is still unclear. Further research is necessary to standardize essential oils formulations, applications dosages and rates, in addition to better understanding their effect on microsclerotia.