A cystic lesion of the renal parenchyma covered by transitional epithelium was known as a renal calyx diverticulum. Although there is no conclusive evidence that calyx diverticulum causes hypertension, there was a strong connection between the 2, and there were a few articles on the subject. The diagnosis and management of a child presenting with a renal calyx diverticulum complicated by hypertension was summarized in the article. The patient, an 11-year-old boy, presented with a left renal cyst and hypertension (155/116 mmHg). There were no related signs or symptoms. Biochemical tests of urine and blood revealed no abnormalities. The hypertension was caused by compression of a left renal cyst, as indicated by imaging. The patient had renal cystic fluid aspiration and a sclerosing agent was injected into the capsule, but the blood pressure rose again 3 days later. According to color Doppler ultrasound, the size of the left renal cyst was the same as preoperatively. To confirm the diagnosis of renal calyx diverticulum, cystoscopic retrograde ureteropyelography was performed. Following this, the renal calicial diverticulum was resected and the calyx neck was widened. The operation went without a hitch and the patient’s blood pressure returned to normal afterwards. At the 7-month follow-up, no abnormalities were discovered. There was a link between renal calyx diverticulum and high blood pressure. Accordingly, hypertension could be used as a surgical indication to remove the renal calyx diverticulum. Also, a renal cyst could easily be mistaken for a renal calicial diverticulum in young people. In such circumstances, it was essential to remain vigilant to avoid a series of consequences, such as postoperative urine leakage.