Polycystic Ovarian Syndrome (PCOS) is a metabolic, reproductive, and endocrine disorder affecting women of fertile age. This study aimed to formulate a phytochemicals-based standardized aqueous ethanolic extract of Rubia cordifolia (SERC) to explore its pharmacological potential in PCOS-induced female rats and elucidate its mechanism. HPLC analysis revealed the presence of phytochemicals such as chlorogenic acid, p-coumaric acid, gallic acid, and kaempferol. Thirty female adult rats were divided into two groups for induction of PCOS (5 female rats in the normal control group + 25 female rats in the disease-induced group). PCOS was induced by administering letrozole (1 mg/kg p.o.) for 6 weeks. After PCOS induction, animals of the disease-induced group were divided into five groups: one group used as disease control (PCOS) group, one group on metformin (20 mg/kg), and three groups on SERC (200, 400, and 600 mg/kg). Histopathological analysis showed that PCOS induction reduced corpus luteum and developing follicles and increased cystic follicles. In comparison, SERC treatment improved ovulation with more primary and developing follicles. SERC reduced the serum insulin, LH surge, and testosterone levels while improving the FSH, estrogen, and progesterone serum levels. SERC significantly improved the oxidation status of the liver and normalized the lipid profile and liver function markers. In conclusion, SERC treated PCOS, and the suggested mechanism might be the restoration of aromatase activity and background inflammatory status improvement in ovaries.