Rationale: The mature cystic teratoma of the ovary (MCTO), is composed of mature differentiated elements, thus showing highly differentiated tissue and highly morphological heterogeneity. Although gastrointestinal epithelium can be identified in 7% to 13% of cases of MCTO, the occurrence of visible, functional, and fully developed loop tissue is rare in clinical practice. Patient concerns: A 17-year-old female patient presented with persistent abdominal pain. Diagnosis: The patient was diagnosed with MCTO where a visible, functional intestinal loop was observed during laparoscopic surgery. Microscopy of the intestinal structure indicated a well-organized, intact layer of intestinal wall. Interventions: An emergency single-port laparoscopic excision of the right ovarian cyst and histopathology were performed. Outcomes: After 2 years of follow-up, there were no signs of recurrence in the patient. Lessons: The immune signature of CK7−/CK20+ is characteristic of tumors of gastrointestinal origin and can be used to distinguish tumors associated with mature cystic teratoma. Besides, gynecologists should keep an eye on the possibility of malignant transformation malignant transformation of MCTO.