Background: Of the 7,678 plant species growing in Mongolia, more than 1,230 are considered medicinal plants; however, around 900 of these remain unstudied, and only about 200 species are currently used in medical practice. In recent years, the use of natural products in therapy has increased, and research in this field has been rapidly developing. Schizonepeta multifida (L.) Briq., a plant belonging to the Lamiaceae family, is widely distributed in Mongolia, Siberia, and East Asia, and is traditionally used to treat colds, fever, and inflammatory diseases. Phytochemical studies have shown that its essential oil contains terpenoid compounds such as pulegone and limonene, as well as flavonoids. These compounds are known to exhibit antioxidant, anti-inflammatory, and neuroprotective effects; however, comprehensive studies on these activities of Schizonepeta multifida growing in Mongolia are limited. Aim: To determine the antioxidant activity, cytotoxicity, and anti-inflammatory effects of Schizonepeta multifita Briq. essential oil and to evaluate its anti-stress effects in an experimental chronic stress animal model. Materials and Methods: The study was conducted at the Institute of Bio-Medicine, Mongolian National University of Medical Sciences. The aerial parts of Schizonepeta multifida were subjected to hydrodistillation using a Clevenger apparatus to obtain essential oil, and the yield was calculated. Antioxidant activity was measured at 517 nm using a spectrophotometer (Agilent BioTek Epoch 2). Cytotoxicity was assessed in BV2 and N2a cell lines using the MTT assay, after which inflammatory markers (IL-6 and TNF-α) were determined in cell cultures using ELISA. For the induction of chronic stress, C57/BL6 mice were divided into healthy control, negative control, and experimental groups. A total of 10 different chronic stress models were randomly applied twice daily for 28 days. Anti-stress effects were evaluated using the forced swim test. Data analysis was performed using Prism 10 software. Results: The yield of essential oil from Schizonepeta multifida was 0.3±0.03%. The antioxidant activity, assessed by the DPPH radical scavenging method, showed an IC₅₀ value of 262.7±2.95 µg/mL, indicating antioxidant potential. Cytotoxicity assays in BV2 and N2a cell lines showed toxic effects starting from a concentration of 200 µg/mL. The essential oil significantly reduced inflammatory markers IL-6 and TNF-α at concentrations of 50, 100, and 200 µg/mL (p<0.05). In the forced swim test, there was a statistically significant difference (p<0.05) between the disease control group and the experimental group. Conclusion The essential oil of Schizonepeta multifida exhibits antioxidant, anti-inflammatory, and anti-chronic stress effects.