Facial gender-affirming surgery can have significant impact on patient quality of life for some gender-dysphoric patients. Lower jaw contouring can be used to harmonize the face during facial gender-affirming surgery through masculinization or feminization. During feminization, the mandibular angle and body and chin are reduced in width and size. During masculinization, augmentation of the mandibular angle and body and chin are completed with alloplastic implants, fat, or bone. Complications are minimal. Further research is needed on outcomes of these procedures.