Augmentative phalloplasty is a controversial issue. A safe, stable, and efficient surgical method for penile girth enlargement has not been available. This article introduces a novel autologous scrotal flap-turning procedure, the scrotal dartos flap method, for men with small penis syndrome and addresses its efficacy and safety. A single-center, prospective study was conducted at the Zhongnan Hospital of Wuhan University, where 29 patients were treated with the scrotal dartos flap method. The key procedure for this technique is fully turning the scrotal dartos flap to the loose plane just between the superficial penile fascia and the Buck fascia to increase the circumference of the penis. Penile girth improvement and adverse events were recorded. Complete follow-up data were collected for 27 of 29 patients (93.1 percent). It yielded a girth improvement of 3.59 ± 0.80 cm (50.8 percent). This enlargement surpassed that of most previous published surgical procedures. In addition, there were no serious adverse events (e.g., penile fibrosis, flap infection, sclerosis, or removal) during the 6-month follow-up. Wound infection ( n = 1), hematoma ( n = 2), and folding ( n = 1) were all slight. This novel autologous flap-turning procedure performed better than the majority of previously published penile girth enlargement methods and was accompanied by only slight and acceptable adverse events. The scrotal dartos flap method appears to be a viable method for the penile girth enlargement treatment of small penis syndrome. Therapeutic, IV.