To report a treatment case of mandibular deviation caused by congenital cervical lymphangioma with traditional orthodontic techniques, following-up by 10-year retention. Lymphangiomas, developmental anomalies, can induce various disturbances of swallowing, mastication, speech, breathing, and skeletal deformities as well as psychological stress and anxiety for the patient and their family. Lymphangiomas are benign with virtually no possibility of turning into a malignant lesion, so clinical management aims to treat the patient functionally. A girl, aged 6 years and 4 months, complained about facial asymmetry and anterior crossbite caused by congenital cervical lymphangioma. Her facial profile was the straight type with an adequate lip position. Anterior and right-side posterior crossbites were observed. On the frontal cephalogram, the menton shifted 3.0 mm to the right. A functional appliance with an expander was placed to correct her dental midline deviation and posterior crossbite. After 2-year treatment, the anterior and right-side posterior crossbites were improved. Multibracket treatment began after the growth spurt. After 44-month active treatment, a functional occlusion, including a Class I molar relationship with a proper interincisal relationship, was achieved. A functional occlusion was maintained during a 10-year retention period, while a mandibular downward growth was observed through the retention period. Conventional orthodontic techniques enable functional and stable occlusion even in patients with mandibular deviation caused by congenital cervical lymphangioma, although only using early orthodontic management by itself may have some limitations. The hybrid technique combining functional appliance and intermaxillary elastics proves to be an effective therapy for correcting occlusal cant and mandibular deviation caused by cervical lymphangioma.