Background: Polycystic Ovary Syndrome (PCOS) is a common endocrine disorder affecting women of reproductive age, often linked to weight gain and metabolic issues. Managing weight effectively reduces PCOS symptoms and enhances reproductive and metabolic health. This study seeks to assess the effects of a structured weight management program on clinical and metabolic parameters in women with PCOS. Methods: This pre-and post-observational study was conducted at Bangabandhu Sheikh Mujib Medical University, Bangladesh, from January 2016 to December 2019. A total of 200 women diagnosed with PCOS are included in this study. Data were collected before and after a 12-week intervention focused on lifestyle modification, including dietary counselling and physical activity. Anthropometric, clinical, and metabolic variables were assessed. Data analysis was performed using SPSS (version 25.0). Paired t-tests were used to compare pre-and post-intervention outcomes, with a significance threshold of p < 0.05. Results: Significant post-intervention improvements were observed in the metabolic, hormonal, menstrual, and psychological parameters in women with PCOS. Reductions were noted in fasting glucose (4.9 ± 0.7 mmol/L), insulin (10.4 ± 3.8 μU/mL), and total testosterone (1.8 ± 0.3 nmol/L). Ovulation frequency increased (3.2 ± 1.7 cycles/year), while depression and anxiety scores significantly declined (p < 0.01 across parameters). Conclusion: A structured weight management approach effectively enhances clinical symptoms and metabolic profiles in women with PCOS. These results highlight the significance of lifestyle intervention as a primary treatment strategy in managing PCOS.