Abstract Background EM has been hypothesized to help prevent the development of ICU acquired weakness and may therefore result in positive outcomes for ICU patients. Aim To establish the impact of Early mobilisation (EM) on adult Intensive Care Unit (ICU) patients in terms of ICU length of stay (LOS), as well as hospital LOS, duration of mechanical ventilation, mortality, and functional independence. Study design A Systematic Review. EMBASE, MEDLINE, CINAHL, and the Cochrane Library were searched on 24th November 2020. Included studies and other systematic reviews were hand‐searched for further includable studies. The primary outcome was ICU LOS whilst secondary outcomes were duration of MV, mortality, hospital LOS and functional independence. The PRISMA guidelines were utilized to perform the review. Ten randomized controlled trials with a combined total of 1291 patients met inclusion criteria and were scrutinized using the Joanna Briggs Institute (JBI) Checklist for Systematic Reviews. Revman 5.4.1 was used to conduct meta‐analysis were possible. Results Results were limited by the evidence available for inclusion, in particular small sample sizes. However, a trend towards a shorter duration of ICU LOS and duration of mechanical ventilation emerged. There was also a trend towards higher rates of functional independence for intervention groups. Mortality rates appeared unaffected and results of meta‐analysis were statistically non‐significant ( p = 0.90). Conclusion By applying a stricter time limit than previous systematic reviews a trend emerged that the commencement of EM has a positive effect on patient outcomes, in particular ICU LOS. Relevance to clinical practice The evidence base surrounding EM remains poor; however on the balance of the available evidence the application of EM should not be delayed.