Seminal vesicle cysts associated with other genitourologic abnormalities are rare. We describe the first known robot-assisted excision of a cystic seminal vesicle associated with ipsilateral renal agenesis in a symptomatic pediatric patient. The patient was discharged home on postoperative day 1 and remains symptom free after 9 months' follow-up. Operative time, blood loss, and hospital stay were comparable to those of published series of conventional laparoscopy.