Reconstruction of functional and aesthetic deformities of the neck after severe burn contracture is challenging. A free anterolateral thigh (ALT) perforator flap may be required, especially if local tissue is affected. To enlarge the surface area of this flap, donor site pre-expansion can be combined with flap transfer. Two patients with large neck defects were treated using pre-expanded free ALT perforator flaps. A rectangular expander was placed under the deep fascia after dissection of the perforator of the descending branch of the lateral circumflex femoral artery. The expansion time was from 3 to 4 months and the final expanded volume was 900-1500 ml. Defect sizes ranged from 14 × 18 to 18 × 27 cm and the expanded ALT flap was measured from 12 × 18 to 27 × 18 cm with one perforator in the flap. After immediate thinning, flap thickness was reduced, ranging from 5 to 11 mm. All flaps survived completely. Two patients were followed for 40 months. The skin color and textures of the flap were good. There was also a clear improvement in appearance and function. In summary, the subfascial expanded ALT perforator flap can be an excellent option for repairing severe neck defects due to its safe harvesting even with the large flaps. The donor area is closed primarily, and the thinned expanded skin is more aesthetically pleasing. The drawbacks are that it is a two-stage procedure, and the expander may be displaced during the expansion period.