Background Task performance is a critical factor for learning in individuals with intellectual disabilities. This study aimed to examine mindfulness‐based intervention (MBI) to improve task performance for children with intellectual disability (ID). Methods Three elementary school children with ID participated in the study. A multiple baseline design across subjects was used. The intervention was consisted of “understanding the necessary concept of mindfulness, practice of awareness and attention, and practice focusing on mindful behaviours.” Mediating materials including expressive arts supplies were used to help each subject to understand the content and the progress of the intervention programme. Results The results showed that all of the three subjects showed an improvement in task performance and a decrease in task‐avoidance behaviours. The mothers reported that her children's daily life behaviours were distinctively improved as he/she participated in the intervention. Conclusion The finding suggests that MBI would be a valuable adjunct to a wide range of applications to support individuals with ID to learn a variety of adaptive behaviour.