Aim: Ovarian cysts can be due to various etiologies and not all ovarian cysts need surgical removal. Background: Ovarian cysts can be functional to neoplastic varying from as small as 3 cm to a full-term gravid uterus. They remain asymptomatic but present lately as acute abdomen requiring emergency surgical intervention. However, ovarian cysts can also be due to an endocrine disorder requiring prompt diagnosis and treatment avoiding inadvertent surgery. Case description: This is a case report of a 13-year-old obese adolescent girl who presented with a 30-weeks palpable abdominopelvic mass. Ultrasound abdomen (USG abdomen) and pelvis revealed a large abdominopelvic multiloculated cystic lesion of size 21 cm × 15 cm × 15 cm. Elective laparotomy was planned. The investigations revealed alarmingly high thyroid stimulating hormone (TSH) values. Endocrinologist opinion was sought and juvenile hypothyroidism was diagnosed and treated with T. Levothyroxine. Surgery was withheld as the patient condition improved. Ultrasound pelvis (USG pelvis) (after 3 months) showed significant size regression to 5 cm × 3 cm, bilateral polycystic ovaries requiring nil surgical intervention. Conclusion: Hypothyroidism should be considered in the differential diagnosis of adolescent females presenting with multicystic ovarian tumors. Adequate thyroid hormone replacement therapy can prevent these patients from undergoing unnecessary and catastrophic ovarian resection. Surgical excision should be considered only when adequate thyroid replacement therapy fails to resolve ovarian enlargement or in emergency cases such as ovarian torsion and rupture.