A cystic lesion in the renal parenchyma covered by the transitional epithelium was known as a renal calyx diverticulum. Although there was no conclusive evidence that the calyx diverticulum causes hypertension, there was a strong link between the 2, and there were a few papers on the subject. The diagnosis and management of a child with renal calyx diverticulum complicated by hypertension were summarised in the paper. The patient, an 11-year-old boy, was found to have a left renal cyst and hypertension (155/116 mmHg). There were no signs or symptoms that were connected. Biochemical tests of the urine and blood revealed no abnormalities. The hypertension was caused by a left renal cyst compression, as indicated by imaging. The patient had a renal cyst fluid aspiration and a sclerosing agent injected into the capsule, but the blood pressure rose again 3 days later. According to color Doppler ultrasonography, the size of the left renal cyst was the same as it was preoperatively. To confirm the diagnosis of renal calyx diverticulum, a cystoscopic retrograde ureteropyelography was done. Following that, the renal calyceal diverticulum was resected, and the calyx neck was enlarged. The operation went without a hitch, and the patient’s blood pressure returned to normal afterward. At the 7-month follow-up, no abnormalities were discovered. There was a link between the renal calyx diverticulum and high blood pressure. As a result, hypertension could be used as a surgical indication to remove the renal calyx diverticulum. Furthermore, a renal cyst could easily be mistaken as a renal calyceal diverticulum in youngsters. In such circumstances, it was critical to remain alert to avoid a series of consequences, such as postoperative urine leakage.