Reactive oxygen species (ROS) are key mediators of several cellular damage and thus associated with equine diseases such as inflammation and metabolic syndrome. This study aimed to evaluate the protective and antioxidant activities of methanolic extract prepared from Cladophora glomerata (C. glomerata) biomass, on equine adipose derived mesenchymal stem cells (EqASCs), under experimental oxidative stress induced by H₂O₂. Pre-treatment of EqASCs cells with different concentrations of C. glomerata methanolic extract (1% and 5%) provided a clear protection against cellular damage triggered by H₂O₂. The cell's apoptotic status was significantly regulated, with promotion of cell viability, down-regulation of pro-apoptotic (p21, p53, Bax and Casp-9) genes expression, concomitant to up-regulation of the survival gene Bcl-2, this being supported by a mitigation of the endoplasmic reticulum (ER) stress and significant minimization of mitochondrial dysfunction. The results also showed that C. glomerata extract significantly increased the antioxidant enzymes Superoxide dismutase (SOD) and Catalase (CAT) activities, positively regulated the enzymes genes expression, and markedly reduced the protein carbonyls derivatives production. Finally, RT-qPCR analysis of the inflammatory related genes allowed to highlight a promising anti-inflammatory and immunomodulatory effect of this extract. Due to the valuable antioxidant and anti-inflammatory activities, C. glomerata may have potential benefits for the prevention of equine diseases associated with oxidative stress, including metabolic syndrome.