Cleft lip and palate is one of the most common congenital abnormalities in the dentofacial region. Orthodontic treatment for adult patients with cleft lip and palate is difficult because of several factors such as dental anomalies, limitations in tooth movement around the cleft region, and retention. Here we report a case involving a 20-year-old woman with unilateral cleft lip and palate who successfully underwent camouflage orthodontic treatment for skeletal Class II malocclusion accompanied by absence of the maxillary left lateral incisor (#22) and second premolar (#25). After a 4-year retention phase, the facial profile and occlusion remained stable, without skeletal or occlusal changes. The findings from this case suggest that an appropriate orthodontic treatment plan and close monitoring during the retention phase can facilitate functional occlusion and esthetic improvement of the facial profile in adult patients with cleft lip and palate.