Background: One-third of stroke patients are dependent on others to get outside their homes. This can cause people to become housebound, leading to increased immobility, poor health, isolation and misery. There is some evidence that outdoor mobility rehabilitation can reduce these limitations. Objective: To test the clinical effectiveness and cost-effectiveness of an outdoor mobility rehabilitation intervention for stroke patients. Design: Multicentre, parallel-group randomised controlled trial, with two groups allocated at a 1 : 1 ratio plus qualitative participant interviews. Setting: Fifteen UK NHS stroke services throughout England, Scotland and Wales. Participants: A total of 568 stroke patients who wished to get out of the house more often, mean age of 71 years: 508 reached the 6-month follow-up and 10 were interviewed. Intervention: Control was delivered prior to randomisation to all participants, and consisted of verbal advice and transport and outdoor mobility leaflets. Intervention was a targeted outdoor mobility rehabilitation programme delivered by 29 NHS therapists to 287 randomly chosen participants for up to 12 sessions over 4 months. Main outcome measures: Primary outcome was participant health-related quality of life, measured by the Short Form questionnaire-36 items, version 2 (Social Function domain), 6 months after baseline. Secondary outcomes were functional ability, mobility, number of journeys (from monthly travel diaries), satisfaction with outdoor mobility (SWOM), psychological well-being and resource use [health care and Personal Social Services (PSS)] 6 months after baseline. Carer well-being was recorded. All outcome measures were collected by post and repeated 12 months after baseline. Outcomes for the groups were compared using statistical significance testing and adjusted for multiple membership to account for the effect of multiple therapists at different sites. Interviews were analysed using interpretive phenomenology to explore confidence. Results: A median of seven intervention sessions [interquartile range (IQR) 3–7 sessions], median duration of 369 minutes (IQR 170–691.5 minutes) per participant was delivered. There was no significant difference between the groups on health-related quality of life (social function). There were no significant differences between groups in functional ability, psychological well-being or SWOM at 6- or 12-month follow-ups. There was a significant difference observed for travel journeys with the intervention group being 42% more likely to make a journey compared with the control group [rate ratio 1.42, 95% confidence interval (95% CI) 1.14 to 1.67] at 6 months and 76% more likely (rate ratio 1.76, 95% CI 1.36 to 1.95) at 12 months. The number of journeys was affected by the therapist effect. The mean incremental cost (total NHS and PSS cost) of the intervention was £3413.75 (95% CI –£448.43 to £7121.00), with an incremental quality-adjusted life-year gain of –0.027 (95% CI –0.060 to 0.007) according to the European Quality of Life-5 Dimensions and –0.003 (95% CI –0.016 to 0.006) according to the Short Form questionnaire-6 Dimensions. At baseline, 259 out of 281 (92.2%) participants in the control group were dissatisfied with outdoor mobility but at the 6-month assessment this had reduced to 77.7% (181/233), a 15% reduction. The corresponding reduction in the intervention group was slightly greater (21%) than 268 out of 287 (93.4%) participants dissatisfied with outdoor mobility at baseline to 189 out of 261 (72.4%) at 6 months. Participants described losing confidence after stroke as being detrimental to outdoor mobility. Recruitment and retention rates were high. The intervention was deliverable by the NHS but had a neutral effect in all areas apart from potentially increasing the number of journeys. This was dependent on the therapist effect, meaning that some therapists were more successful than others. The control appeared to affect change. Conclusions: The outdoor mobility intervention provided in this study to these stroke patients was not clinically effective or cost-effective. However, the provision of personalised information and monthly diaries should be considered for all people who wish to get out more.