Polycystic ovary syndrome (PCOS) is a complex endocrine disorder that affects women of reproductive age, characterized by androgen-induced oxidative stress leading to several metabolic disorders. In this study, we investigated the potential therapeutic effect of caffeic acid on PCOS and its underlying molecular mechanism. We used a human ovarian granulosa cell line (KGN cells) induced by hydrogen peroxide (H₂O₂) to examine how caffeic acid influences the protein expression of oxidative stress-induced apoptosis-related markers. Our results indicate that caffeic acid significantly inhibits intracellular reactive oxygen species (ROS) generation and safeguards KGN cells against oxidative stress. For the in vivo aspect of our study, female Sprague-Dawley (SD) rats were utilized to induce the PCOS model using dehydroepiandrosterone (DHEA). Caffeic acid was then administered to the rats for a duration of 6 weeks. The outcomes revealed that caffeic acid effectively improved irregular estrous cycles, fasting blood glucose levels, liver function, and lipid profiles in DHEA-induced PCOS rats. Additionally, it mitigated hyperandrogenism, enhanced steroidogenesis enzyme expression, and modulated apoptosis-related protein expression. Our findings strongly suggest that caffeic acid holds promising potential in reducing oxidative stress-induced damage and ameliorating PCOS-related complications by modulating ER stress.