Background In performing extended latissimus dorsi (ELD) flap procedures, a skin paddle design on the bra line helps reduce visible scarring. This improves the patient’s satisfaction with the outcome. However, such a design leads to a longer operation time and increased fatigue of the surgeon due to the narrow operative field. In this study, the authors propose a method that elongates the axillary incision line posteriorly by 1.5 cm from the lateral border of the latissimus dorsi muscle. We examined whether this method could shorten the operation time and compared the incidence of complications between patients who underwent this novel procedure and patients who underwent the traditional procedure. Methods In this study of patients who underwent ELD flap procedures for immediate breast reconstruction, 89 underwent surgery with the elongated axillary incision and 45 underwent surgery without the elongated incision. The total operation time and complications were retrospectively examined based on the patients’ medical records, and we examined whether there was any statistically significant difference in the total operation time. Results In the experimental group with the elongated axillary incision, the operation time ranged from 125 to 255 minutes (median, 175 minutes). In contrast, in the control group without the elongated axillary incision, the operation time ranged from 142 and 340 minutes (median, 205 minutes). The operation time was statistically significantly different between the two groups, and no significant complications were observed in the experimental group. Conclusions Elongation of the axillary incision alone may shorten the operation time of the ELD flap procedure without causing additional complications.