Purpose: To evaluate the onlay technique using the appendix for ureteral reconstruction and describe the initial experience of nine operations performed by one surgeon. Methods: Nine patients with complex ureteral strictures who underwent appendiceal onlay flap ureteroplasty since May 2019 were recruited from our RECUTTER database. There were seven men and two women, with a mean age of 38.9 years; four patients underwent robot-assisted laparoscopic surgery, and five patients underwent traditional laparoscopic surgery. All patients had iatrogenic injuries of the ureter after treatment of stone disease. Seven patients had proximal ureteral strictures, and two had midureteral strictures. The mean stricture length of the nine patients was 3.9 (range 3-4.5) cm. Nephrostomy was performed in seven patients before they presented to our center, and the other two patients had indwelling Double-J ureteral stents. Results: All nine operations were effectively completed without open conversion. The mean operation time was 182 (range 135-220) minutes, the mean estimated blood loss was 71 (range 20-100) mL, and the mean length of postoperative hospital stay was 9 (range 6-12) days. No postoperative complications of high grade (Clavien-Dindo III and IV) occurred within 30 days of surgery. All the patients had their Double-J ureteral stents and nephrostomy tubes removed after complete ureteroscopy and upper urinary tract urodynamic examination or CTU, which showed that the anastomosis healed well and that the urinary tract was unobstructed, respectively. The objective success rate was 100% (all the patients had endoscopic and radiographic resolution of their ureteral strictures). The subjective success rate was 88.9% (one patient developed recurrent back discomfort and a 0.5 cm calculus was found in her renal pelvis). Conclusions: Appendiceal onlay flap ureteroplasty is a viable and effective technique for treating complex proximal and middle ureteral strictures at the right side.