Background: Cleft lip and palate (CLP) is a congenital anomaly that accounts for approximately 65% of all craniofacial malformations. In Mongolia, the prevalence of CLP is estimated at 0.93 to 1 per 1,000 live births, which is comparable to the global average but slightly higher than the average reported among Asian countries. The incidence is observed to be twice as common in males compared to females. Diagnosis: The patient is a 15-year-old male with a history of congenital unilateral cleft lip and palate. He underwent primary surgical repair of the cleft at the age of 9. As of May 2022, clinical examination revealed maxillary hypoplasia, anterior crowding, and a combination of bilateral posterior and anterior crossbite. Cephalometric analysis demonstrated a skeletal Class III malocclusion with midfacial deficiency. Treatment: Orthodontic treatment was initiated in October 2022 using a non-removable, self-ligating bracket system (MBT 0.022” slot, stainless steel). In the first month, CuNiTi 0.014 archwires were placed, and cross elastics were applied from the maxillary to mandibular canines on the left side for two months. On December 10, 2022, CuNiTi 0.014×0.025 archwires were placed in both arches, accompanied by coil springs to open space. Subsequent phases involved transitioning to stainless steel (SS) and titanium-molybdenum alloy (TMA) archwires for alignment and leveling. Treatment Outcome: At the end of treatment, a Class I molar and canine relationship was achieved. The axial inclinations of the upper and lower incisors reached normative values based on lateral cephalometric analysis. The maxillary arch form was expanded and improved to a more ideal rounded contour. Dental crowding was resolved without extraction, and both transverse and sagittal occlusal relationships were significantly improved. Conclusion This clinical case demonstrates that fixed orthodontic treatment in a patient with unilateral cleft lip and palate can effectively correct dental crowding, normalize occlusal relationships, and significantly improve facial esthetics, phonetics, and overall quality of life. Orthodontic intervention played a vital role in restoring function and supporting psychosocial and physical development.