Children with Trisomy 21 generally have delayed psychomotor development and intellectual disabilities that can compromise the acquisition of motor and communication skills. The study is based on the hypothesis that music can be a beneficial auxiliary resource in Occupational Therapy sessions, due to its influence on the human body, and can be useful to promote participation. The objective of the research was to observe the effect of music on maintaining the child's attention, participation and involvement in different tasks in Occupational Therapy sessions, defined based on demands defined by the Canadian Occupational Performance Measure (COPM). This is a single case study with a 4-year-old child, diagnosed with Trisomy 21. After 12 sessions there was an improvement in the child's performance in the demands brought by the mother, as well as an improvement in their satisfaction in the activities carried out. The comparative analysis shows an increase of 5.6 points in the child's performance and an increase of 6.3 points in the mother's satisfaction in the reevaluation. Music in this study provided a positive result in the proposed activities, helping the child to maintain attention, increasing participation and independence in brushing teeth, getting dressed and drinking water from the glass.