BACKGROUND: Recently, robotic surgery has become more common as a minimally invasive treatment for gastric cancer (GC) and rectal cancer (RC). Herein, we report successful simultaneous robotic gastrectomy and low anterior resection in a patient with advanced GC and RC. CASE PRESENTATION: A 76-year-old woman who presented with bloody stool was found to have advanced GC with lymph node metastases and advanced RC. Simultaneous robotic distal gastrectomy with D2 lymph node dissection and Billroth I reconstruction and low anterior resection with D3 lymph node dissection were performed. Preoperatively, multidisciplinary medical staff discussed the case in detail and conducted a simulation with the robot, operating room, and patient. The total operative time was 648 min (console time, 520 min), and the estimated blood loss was small. The patient was discharged on postoperative day 10 without any adverse events. In this case, careful simulation of the patient cart setting and planning of the best port layout resulted in a successful surgical outcome despite this being our first simultaneous total robotic surgery for advanced GC and RC. CONCLUSIONS: Simultaneous robotic surgery for advanced GC and RC may be technically feasible and could provide an option for future minimally invasive treatment.