Undifferentiated small round cell sarcoma (USRCS) is a rare malignant tumor. No reports about USRCS of the postcricoid region of the hypopharynx are available, and its clinical features and treatment guidelines remain undefined. We report a case of USRCS of the postcricoid region of the hypopharynx with treatment of surgery and radiotherapy. A 50-year-old man presented with a 4.9 cm x 3.7 cm tumor in the postcricoid region of the hypopharynx. It was diagnosed as USRCS. The tumor showed small round cells and positive immunoexpression of CD56, Cyclin D1, TLE1 and CD99, but no rearrangement or fusion of EWSR1, SS18, CIC, and BCOR. The patient underwent radiotherapy after surgery, without signs of tumor progression and metastasis at the 9-month follow-up. In conclusion, USRCS of postcricoid region of hypopharyngeal is ultra-rare. To make diagnosis, pathological examination is necessary. Surgery followed by radiotherapy might offer an optional treatment for USCRS.