This study analyzed the chemical composition and antimicrobial and antioxidant activities of four oregano essential oils (OEOs) from Poland, Europe, Turkey, and the USA. The main component of all OEOs was carvacrol, which ranged from 76.64% to 85.70%. The highest concentration of carvacrol was found in the Polish OEO. The OEOs showed strong antimicrobial activity, particularly against fungi, with minimum inhibitory concentrations (MICs) ranging from 0.06 to 0.25 mg/mL. They also exhibited high antioxidant activity, with values ranging from 71.42% to 80.44%. The OEOs demonstrated significant antimicrobial and antioxidant properties, making them promising candidates for further research as natural antimicrobial and antioxidant agents. The study also found correlations between the chemical composition of the OEOs and their antimicrobial and antioxidant activities, highlighting the importance of carvacrol and other components in determining these properties. The results suggest that OEOs, particularly those with high carvacrol content, could be valuable in combating antimicrobial resistance and as natural alternatives to synthetic antimicrobial agents.This study analyzed the chemical composition and antimicrobial and antioxidant activities of four oregano essential oils (OEOs) from Poland, Europe, Turkey, and the USA. The main component of all OEOs was carvacrol, which ranged from 76.64% to 85.70%. The highest concentration of carvacrol was found in the Polish OEO. The OEOs showed strong antimicrobial activity, particularly against fungi, with minimum inhibitory concentrations (MICs) ranging from 0.06 to 0.25 mg/mL. They also exhibited high antioxidant activity, with values ranging from 71.42% to 80.44%. The OEOs demonstrated significant antimicrobial and antioxidant properties, making them promising candidates for further research as natural antimicrobial and antioxidant agents. The study also found correlations between the chemical composition of the OEOs and their antimicrobial and antioxidant activities, highlighting the importance of carvacrol and other components in determining these properties. The results suggest that OEOs, particularly those with high carvacrol content, could be valuable in combating antimicrobial resistance and as natural alternatives to synthetic antimicrobial agents.