Early active mobilisation and rehabilitation in the intensive care unit (ICU) is being used to prevent the long-term functional consequences of critical illness. This review aimed to determine the effect of active mobilisation and rehabilitation in the ICU on mortality, function, mobility, muscle strength, quality of life, days alive and out of hospital to 180 days, ICU and hospital lengths of stay, duration of mechanical ventilation and discharge destination, linking outcomes with the World Health Organization International Classification of Function Framework.A PRISMA checklist-guided systematic review and meta-analysis of randomised and controlled clinical trials.Fourteen studies of varying quality including a total of 1753 patients were reviewed. Active mobilisation and rehabilitation had no impact on short- or long-term mortality (p > 0.05). Meta-analysis showed that active mobilisation and rehabilitation led to greater muscle strength (body function) at ICU discharge as measured using the Medical Research Council Sum Score (mean difference 8.62 points, 95% confidence interval (CI) 1.39-15.86), greater probability of walking without assistance (activity limitation) at hospital discharge (odds ratio 2.13, 95% CI 1.19-3.83), and more days alive and out of hospital to day 180 (participation restriction) (mean difference 9.69, 95% CI 1.7-17.66). There were no consistent effects on function, quality of life, ICU or hospital length of stay, duration of mechanical ventilation or discharge destination.Active mobilisation and rehabilitation in the ICU has no impact on short- and long-term mortality, but may improve mobility status, muscle strength and days alive and out of hospital to 180 days.CRD42015029836.