Low-grade endometrial stromal sarcoma (LGESS) is a rare malignant tumor of the uterus, often misdiagnosed due to its indolent progression and nonspecific clinical presentation. We report the case of a 49-year-old perimenopausal woman who presented with abnormal uterine bleeding and pelvic pain. Pelvic ultrasound and MRI revealed a heterogeneous uterine mass. The patient underwent a total hysterectomy, and definitive histopathology confirmed the diagnosis of LGESS. This case underscores the importance of including LGESS in the differential diagnosis of abnormal uterine bleeding in perimenopausal women. Early diagnosis and complete surgical excision remain the cornerstone of treatment, and long-term follow-up is crucial due to the risk of late recurrence.