Background: Only about 9% of individuals with intellectual disabilities reach the government's physical activity (PA) recommendations. Combining gamification and technology seems particularly promising in overcoming personal and environmental barriers to PA participation. Method: Eighteen adults with varying levels of intellectual disabilities completed a pilot study to assess the initial effects of a cycling gamification intervention on levels of PA, fitness, psychosocial outcomes, and challenging behaviours. The study comprised three designs: pre-post single group, AB single-case, and qualitative. Social validity, implementation barriers and facilitators were also explored. Results: Nearly all 18 participants cycled daily. Time and distance cycled daily increase during the intervention while a decrease in stereotyped behaviours was observed. Participants and staff found the intervention enjoyable and socially valid. Conclusions: Results of the multiple-design study suggest that gamification interventions may be a suitable, enjoyable, and promising way to contribute to PA participation of adults with intellectual disabilities.