Abstract: The effects of methyl jasmonate (MeJA) on the synthesis of antioxidant compounds in Lavandula angustifolia Mill. leaf suspension cells were investigated by introducing varying concentrations of MeJA into the culture medium. The optimal conditions for enhancing antioxidant synthesis were determined, and non-targeted metabolomics was employed to analyze the impact of MeJA on metabolite production. Results demonstrated that 8 mg/L MeJA inhibited both cell growth and antioxidant activity, whereas 2 mg/L MeJA significantly promoted the biosynthesis of antioxidant compounds. Compared with the untreated group, cells treated with 2 mg/L MeJA exhibited a 1.30-fold increase in ABTS radical scavenging activity and a 2.56-fold increase in ferric reducing antioxidant power (FRAP). Additionally, total phenol, flavonoid, and triterpene contents were elevated by 1.45-fold, 1.59-fold, and 1.24-fold, respectively. Metabolomic profiling using UHPLC-Q-TOF-MS identified 1 403 metabolites, with 151 showing significant differences between untreated and MeJA-treated cells. These differential metabolites were associated with 177 metabolic pathways, predominantly enriched in metabolic pathways and ABC transporter pathways. These findings suggest that MeJA modulates antioxidant biosynthesis in L. angustifolia suspension cells primarily by influencing metabolic signal transduction and regulating ABC transporter activity.