Background Nasal alarplasty is an important component of esthetic rhinoplasty in Asians. The two main surgical techniques that correct alar hypertrophy by reducing the height or length often leave external scars and are associated with a high relapse rate. Methods We developed a new technique, called three-dimensional (3D) M-shaped resection, which corrects both the nasal alar height and length and simultaneously minimizes external scarring. We performed this procedure from January 2013 to September 2016 in 49 consecutive female patients diagnosed with saddle nose and nasal alar hypertrophy. Their mean age was 28.6 (range, 18–40) years. All patients had previously undergone simple rhinoplasty. Nasal alar length and height, nostril length and width, and maximal nose width were analyzed preoperatively and postoperatively from photographs. Results After a mean of 9 (range, 3–24) months of follow-up, surgery was considered successful in 46 women (94％) with good cosmetic effects. In three patients, nasal alar hypertrophy recurred (6 months postoperatively). There were no early complications such as hematomas, infections, skin or mucosal necrosis, or wound dehiscence. The mean reductions postoperatively were 1.7 mm and 0.9 mm for nasal alar length and height, respectively, 1.6 mm for both nostril length and width, and 3.5 mm for nose width. Conclusion The 3D M-shaped resection for nasal alar hypertrophy effectively reduced hypertrophy in 94％ of patients for up to 24 months, producing minimal external scars and good cosmetic effects. It is a simple and convenient technique that is an effective and safe option for nasal alarplasty.