The unicornuate uterus is a rare congenital uterine anomaly. Most unicornuate uteri present with contralateral rudimentary horn uterus with functional endometrium. Patients with functional rudimentary horn uterus usually present with dysmenorrhea and may complicate with malformation of fallopian tube and urinary system. Transvaginal pelvic ultrasound is the first-line diagnostic method, and hysteroscopic-united laparoscopic examination is the gold standard for diagnosis. Rudimentary horn uterus and the ipsilateral fallopian tube resection should be performed once diagnosed to relieve symptoms and to prevent rudimentary horn uterus pregnancy. Postoperative management should focus on monitoring adverse obstetrics outcomes such as recurrent pregnancy loss, intrauterine growth restriction, and preterm delivery.