ObjectiveTo determine the effectiveness of mindfulness-based programmes (MBPs) on the mental health of elite athletes.DesignSystematic review and meta-analysis.Data sourcesEight online databases (Embase, PsycINFO, SPORTDiscus, MEDLINE, Scopus, Cochrane CENTRAL, ProQuest Dissertations & Theses and Google Scholar), plus forward and backward searching from included studies and previous systematic reviews.Eligibility criteria for selecting studiesStudies were included if they were randomised controlled trials (RCTs) that compared an MBP against a control, in current or former elite athletes.ResultsOf 2386 articles identified, 12 RCTs were included in this systematic review and meta-analysis, comprising a total of 614 elite athletes (314 MBPs and 300 controls). Overall, MBPs improved mental health, with large significant pooled effect sizes for reducing symptoms of anxiety (hedgesg=−0.87, number of studies (n)=6, p=0.017,I2=90) and stress (g=−0.91, n=5, p=0.012,I2=74) and increasing psychological well-being (g=0.96, n=5, p=0.039.,I2=89). Overall, the risk of bias and certainty of evidence was moderate, and all findings were subject to high estimated levels of heterogeneity.ConclusionMBPs improved several mental health outcomes. Given the moderate degree of evidence, high-quality, adequately powered trials are required in the future. These studies should emphasise intervention fidelity, teacher competence and scalability within elite sport.PROSPERO registration numberCRD42020176654.