BACKGROUND: Pre-fabricated myofunctional appliances for early orthodontic therapy have been designed specifically for the care of children at the time of mixed dentition in growing adolescents with class II division 1 malocclusions. Sophisticated prefabricated removable functional appliances known as pre-orthodontic trainers have been shown to train the orofacial musculature, thus correcting malocclusions. CASE DESCRIPTION: This is a case report of 9-year-old boy diagnosed as Class II division 1 malocclusion with protruded upper anterior teeth, constricted upper arch, space loss in lower arch and Class 2 molar relation on side. Functional treatment approach was decided using pre orthodontic T4K trainer for 12 months. At the end of this phase of treatment, improvements have been evaluated with lateral cephalograms superimposition between T1 and T2. DISCUSSION: Class II orthopaedic treatment along with the use of functional appliances by early interception assist in addressing the concerns with soft tissues, muscles, mouth respiration, and bruxism. The pre orthodontic trainer allowed a good dento-skeletal result as it had a major effect on the masticatory muscles after 12 months application which helped in obtaining a good esthetic outcome for the patient. CONCLUSIONS: The use of prefabricated functional appliance in children can be an advantageous method for early treatment of class II malocclusions with functional patterns as these devices influences masticatory muscle which help in molding the facial tissues and a viable alternative to braces for treating malocclusions in children because it stimulates the development of the dental arches transversely to stop the progression of the malocclusion. Therefore, when a lack of transverse development is discovered at a young age, this appliance is an invaluable tool for enhancing dental arch development, interceptive management of malocclusion, and oral habits.