Essential oils are derived from aromatic plants and can be extracted from various parts, including flowers, leaves, bark, fruit, seeds, and other important parts of the plant. Historically, these oils have been utilized for their therapeutic properties and continue to be an integral part of folk medicine across diverse cultures, owing to their multifaceted and remarkable medicinal benefits, which encompass antioxidant, anti-inflammatory, analgesic, anti-cancer, liver-protective, and neuroprotective properties, among others. As part of the “Albread” project, supported by the Promove 2023 competition and titled “Aromatic plants from Alentejo, probiotics, and acorn flour in the development of functional bread”, this study aimed to investigate the antioxidant potential of essential oils marketed by companies in the Alentejo and Algarve regions of Portugal. A total of 21 essential oils were evaluated for their antioxidant capacity using two widely used methodologies: DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging and ABTS (2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) radical scavenging assays. The solvent employed for diluting the essential oils in this study was 70% ethanol, with Trolox serving as the standard, and all tests were conducted in triplicate. The results indicated a successful differentiation of the antioxidant potential of the essential oils across both methodologies. The DPPH method revealed antioxidant activity ranging from 0.039 to 0.518 mgTE/gEOW, while the ABTS method demonstrated a range of 0.21 to 3.08 mgTE/gEOW. It can be concluded that the 21 essential oils assessed from Portuguese companies exhibited variability in their antioxidant potential but maintained comparable patterns between the DPPH and ABTS methods. Essential oils 11, 12, and 13 exhibited the highest antioxidant activity, whereas oil 7 demonstrated the lowest potential.