Congenitally missing maxillary lateral incisors present a significant esthetic and functional challenge, particularly in young adults with high esthetic expectations. Although implant-supported restorations are frequently considered, anatomical limitations may preclude implant placement. Single-retainer cantilever resin-bonded fixed dental prostheses (RBFDPs) represent a minimally invasive alternative that preserves the integrity of adjacent teeth. It is about a 26-year-old female patient with bilateral congenital absence of the maxillary lateral incisors was referred for definitive prosthetic rehabilitation following orthodontic space opening. The adjacent central incisors and canines were intact, caries-free, and periodontally healthy. Although implant-supported rehabilitation was initially planned, preoperative cone-beam computed tomography revealed insufficient residual ridge dimensions for implant placement. Two single-retainer cantilever RBFDPs were therefore selected. The prostheses were fabricated from lithium disilicate-reinforced glass-ceramic using a digital CAD/CAM workflow and bonded to the palatal surfaces of the maxillary central incisors. Treatment involved conservative enamel-dominant preparations, soft-tissue management, immediate dentin sealing of localized exposed dentin, digital prosthetic design, and adhesive resin cementation. At completion, the restorations demonstrated satisfactory adaptation, esthetic integration, and functional occlusion, and the patient reported satisfaction with the outcome. Within the limitations of a single case report, lithium disilicate single-retainer cantilever RBFDPs provided a conservative and esthetically satisfactory treatment option for replacing congenitally missing maxillary lateral incisors while preserving the possibility of future implant therapy. Long-term follow-up is required to evaluate the durability and clinical stability of this approach.