RTx of adult-size kidneys presents a size mismatch in small pediatric recipients, and there are potential surgical complications. This study reveals the outcomes of intra- and extraperitoneal RTx in low-weight (less than 15 kg) pediatric recipients. We studied 51 pediatric patients weighing less than 15 kg who received a living-related donor renal transplant between 2009 and 2017. The intraperitoneal (group A, n = 24) and extraperitoneal (group B, n = 27) approaches were compared. In group A, the mean age, Ht, and weight were 3.8 ± 1.6 years, 83.7 ± 6.5 cm, 10.5 ± 1.8 kg; in group B, 5.0 ± 1.9 years, 95.3 ± 7.3 cm, and 13.0 ± 1.4 kg. Single renal artery grafts (21 in group A and 16 in group B) and double renal artery grafts (three in group A and 11 in group B) were performed. Of the patients with double renal artery transplants, one in group A and six in group B underwent ex vivo arterial reconstruction. The eGFR (mL/min/1.73 m² ) at 1-week post-transplant in group A was significantly higher than that in group B; the eGFRs at 4 weeks post-transplant did not differ. One graft was lost in group B because of vascular thrombosis. Post-transplant complications included ileus and transplant ureteral stenosis. There was no significant difference in 5-year graft survival rate (group A 100%, group B 91.7%). Both transplant approaches are feasible to adapt to a size mismatch between the adult-size donor kidney and low-weight pediatric recipients.