Skin-reducing mastectomy for single-stage reconstruction is an oncologically safe procedure used in women with large and ptotic breasts. This study describes a new technique, the J-pattern skin-reducing breast reconstruction with prepectoral implant and acellular dermal matrix (Braxon fast), which is indicated for patients with large and ptotic breasts who would benefit from a breast reduction and need a mastectomy for curative or prophylactic purposes. The authors present a case series of 35 breasts of 19 women who underwent this procedure from January of 2021 through December of 2022 at the Plastic and Reconstructive Surgery Department of the University Hospital Santa Maria della Misericordia, in Udine, Italy, with a median follow-up of 15 months. The advantages of the J scar consist of a reduced risk of skin necrosis, a reduced bottoming-out rate, simplification of the surgical design, and lower impact of scars not involving the medial quadrants of the breast. Patients were administered the BREAST-Q 2.0 postoperative questionnaire at 3 months postoperatively, which showed a high average level of satisfaction with the reconstruction. This surgical technique is a valid option for patients who have voluminous breasts and adequate pinch test results who wish to undergo immediate heterologous reconstruction along with curative or prophylactic mastectomy. Therapeutic, IV.