Physical activity is a key factor for healthy ageing, yet many older people lead a sedentary lifestyle. Traditional physical activity interventions do not consider the specific needs and views of older adults. As views on ageing are known to be related to health behaviours, the current study evaluates the effectiveness of prompting positive views on ageing within a physical activity intervention. Randomised controlled trial with three groups aged 65+: Intervention for physical activity with views-on-ageing-component (n = 101; IGVoA), and without views-on-ageing-component (n = 30; IG), and active control intervention for volunteering (n = 103; CG). Attitudes towards older adults and physical activity were assessed five weeks before intervention, two weeks, six weeks and 8.5 months after the intervention. Compared to the IG and CG, positive attitudes towards older adults increased in the IGVoA after the intervention. For IGVoA, the indirect intervention effect on change in activity via change in attitudes towards older adults was reliable. A views-on-ageing-component within a physical activity intervention affects change in physical activity via change in views on ageing. Views on ageing are a promising intervention technique to be incorporated into future physical activity interventions for older adults.