An ectopic kidney is a rare congenital defect in which the kidney does not migrate to its normal anatomical position. In the present study, a robot-assisted radical cystectomy and intracorporeal urinary diversion were performed for a patient with an ectopic kidney. The present study describes the case of a 72-year-old male patient who was diagnosed with a bladder tumor by magnetic resonance imaging and cystoscopy. A transurethral resection of the bladder tumor was performed. The pathological examination revealed an invasive urothelial carcinoma. Contrast-enhanced computed tomography revealed an ectopic left kidney in the upper pelvis. A robot-assisted radical cystectomy, extended lymph node dissection and intracorporeal urinary diversion were performed. On the whole, as demonstrated herein, a robot-assisted radical cystectomy with intracorporeal urinary diversion is a feasible approach for muscle-invasive bladder cancer complicated by an ectopic kidney.