Introduction: Increased oxidative stress in obese individuals accelerates the onset of cellular senescence. Coriander seed (Coriandrum sativum L.) contains natural antioxidants that may reduce oxidative stress. This study aimed to assess the effects of coriander seed extract on oxidative stress and cellular senescence in the livers of rats with diet-induced obesity. Methods: Coriander seed ethanolic extract (100 mg/kg body weight) was administered to obese rats 12 weeks after obesity induction. Body weight, Lee index, body mass index, and plasma lipids were measured at 12 and 24 weeks. Liver tissue was analysed for malondialdehyde (MDA), catalase-specific activity, senescence-associated β-galactosidase (SA-β-Gal) activity, and p16INK4A expression. Plasma lipid profile, liver histology, and liver function were also evaluated. Results: Coriander seed extract did not significantly reduce body weight, Lee index, or body mass index in obese rats, but it decreased plasma triglycerides. Both plasma and liver MDA levels were significantly reduced, and catalase-specific activity was increased. Expression of p16INK4A decreased, although SA-β-Gal activity was not significantly affected. Histological analysis revealed lower non-alcoholic steatohepatitis (NASH) scores in the livers of coriander-treated obese rats, supported by decreases in alanine aminotransferase and aspartate aminotransferase levels. Discussion: Coriander seed extract mitigated hepatic oxidative stress, suppressed hepatocellular senescence, and improved liver function in obese rats. These findings suggest hepatoprotective activity of coriander seed extract in obesity, with potential clinical relevance pending confirmation of safety in preclinical toxicity studies. Conclusion: Coriander seed ethanolic extract protects liver tissue in high-fat diet–induced obese rats from oxidative stress and cellular senescence. 2026, Bentham Science Publishers