Background: The purpose of this study was to investigate the patterns of objectively measured sedentary behaviour in adults with intellectual disabilities. Methods: Baseline accelerometer data were pooled from two randomized controlled trials of lifestyle behaviour change programmes for adults with intellectual disabilities. Patterns of sedentary behaviours were computed including total volume, number, and duration of bouts and breaks. Results: Participants spent >70% of the day sedentary (8 hr), which was generally accumulated in short sedentary bouts (<10 min). Participants were engaged in significantly more sedentary time during the morning, although differences between time of day were small (mean bout duration range: 19.8-22.3 min). Conclusions: The findings add valuable insight into the patterns of sedentary behaviours among adults with intellectual disabilities. Further research investigating the patterns and context of sedentary behaviour is required to develop targeted interventions to reduce total sedentary time in adults with intellectual disabilities.