The main purpose of this study was to meta-analyse the single-case studies on the use of activity schedules with individuals with autism spectrum disorders. The other purposes were to assess the design standards of activity schedule studies, estimate the treatment effect of activity schedule, describe the characteristics of activity schedule studies, and determine whether activity schedule is an evidence-based practice for children with autism spectrum disorders in improving appropriate behaviours. The nonoverlap of all pairs (NAP) was used to analyse the treatment effect measure. According to results, seven out of 32 activity schedule studies met the design standards with and without reservation. Twenty-four children with autism spectrum disorders whose age ranged between 3 and 17 years participated in the studies. The target behaviours were on task, independent transition, appropriate peer-play, and following schedule. The photographs and texts were used in both traditional and innovative activity schedules. The overall NAP score shows that the activity schedule has a strong effect for those participants with autism spectrum disorders. Finally, this meta-analysis indicates that an activity schedule can be recommended as an evidence-based practice to improve the appropriate behaviours of children with autism spectrum disorders.