Herbs are considered substantial sources of antioxidant compounds, playing an important role in medicines, cosmetics, and distillates. Although they have been used in wine since ancient times, especially in Mediterranean regions, there is limited scientific evidence on how the addition of herbs into wine affects its properties. The aim of the present study was to determine the effects of three herbs, Salvia officinalis, Melissa officinalis and Cannabis sativa, with direct extraction in two different conditions: in must (pre-fermentation addition) and in wine (post-fermentation addition) and investigate potential differences between them. Three Greek indigenous grape varieties of Vitis vinifera L. were evaluated (Roditis, Muscat, Fokiano). The extractability of phenolic compounds and the antioxidant capacity of the produced wines were determined by the Folin–Ciocalteu and DPPH methods, respectively. Moreover, HPLC analysis was conducted to identify and quantify rosmarinic acid and caffeic acid, two main components of many Lamiaceae plants. The results indicate that the post-fermentation addition of herbs leads to a significant increase in antioxidant activity and phenolic compounds compared to blank wine. In most cases, the increase is significantly higher in comparison with pre-fermentation addition. Wine, upon the addition of Melissa officinalis, was found to extract the highest amount of total phenols compared to the other two herbs.