When a malignant tumor is located at proximal lower limb, hip joint disarticulation must be considered. Free fillet flap harvested from the amputated limb provides an excellent source of vascularized tissues for reconstruction of the large soft tissue defect following tumor resection by means of hip joint disarticulation without additional donor site. We report a 57- year-old male patient who suffered from recurrent right thigh fibrosarcoma. Right hip disarticulation with free fillet flap reconstruction was performed, and the wound healed well. Three months later, a custom-made lower limb prosthesis was fitted successfully, and the patient could then walk with the assistance of a walker.