Aegopodium podagraria L. (goutweed), a member of the Apiaceae family, is a common perennial plant found all around the world that has been used in folk medicine since antiquity. Goutweed leaves contain polyacetylenes, essential oils, mono- and sesquiterpenes, vitamins, macro- and microelements, and phenolic compounds. In spite of its many health-promoting properties, including antioxidant effects, the plant has not been thoroughly studied. The aim of this study was to investigate the antioxidant properties of different goutweed leaf extracts and their effects on the THP-1 cell line, and also to describe the chemical characteristics of goutweed. Falcarinol and falcarindiol and essential oil were determined by gas chromatography coupled with mass spectrometry. Spectrophotometry was used to measure the total content of polyphenols and antioxidant activity–by DPPH and FRAP methods. Oxidative stress in THP-1 cells was induced via sodium fluoride. Then, goutweed leaf extracts were added to evaluate their influence on antioxidant potential (ABTS) and the activity of antioxidant enzymes. Confocal microscopy was used to visualise the production of cytoplasmic and mitochondrial reactive oxygen species (ROS) and for in vitro imaging of apoptosis. The ethanol extracts have a high total content of polyphenols, polyacetylenes, and essential oil, as well as high antioxidant potential. The main volatiles represented diverse chemical groups, which are both oxygenated derivatives of sesquiterpenes and monoterpenes. We also demonstrated positive effects of the high antioxidant potential and increased activity of antioxidant enzymes on cell cultures under severe fluoride-induced oxidative stress. Extraction at 80 ℃ and the use of ethanol as a solvent increased the antioxidant capacity of the extract. The leaves of Aegopodium podagraria may serve as a valuable source of antioxidants in the daily diet and assist in the prevention and treatment of oxidative stress-mediated conditions, e.g., inflammatory conditions, cardiovascular diseases, neurodegenerative diseases, and even obesity.