Objective: To investigate the impact of Tai Chi training on muscle strength, physical endurance, postural balance and flexibility, as measured by tests commonly used in health-related fitness or competitive sports contexts. Design: Systematic review and meta-analysis. Data sources: The following databases were searched up to 31 July 2020: CINAHL, Cochrane Library, MEDLINE via PubMed and SPORTDiscus. Eligibility criteria for studies: Inclusion: (1) Randomised controlled trials published in German or English; (2) Tai Chi used as an intervention to improve physical performance; (3) Test methods commonly used in health-related fitness or competitive sports and (4) Participants aged ≥16 years (irrespective of health status). Exclusion: (1) Studies not focusing on Tai Chi or including Tai Chi mixed with other interventions and (2) Modified or less than eight Tai Chi movements. Results: Out of 3817 records, 31 studies were included in the review, 21 of them in the meta-analysis. Significant improvements in handgrip strength (2.34 kg, 95% CI 1.53 to 3.14), walking distance during 6 min (43.37 m, 95% CI 29.12 to 57.63), standing time in single-leg-stance with open eyes (6.41 s, 95% CI 4.58 to 8.24) and thoracolumbar spine flexibility (2.33 cm, 95% CI 0.11 to 4.55) were observed. Conclusion: Tai Chi training seems to moderately improve physical fitness when evaluated by tests used in health-related fitness or competitive sports. Moreover, thoracolumbar spine flexibility seems to be a factor in the improvement of postural balance. Further research is needed, including younger healthy participants performing a widely used, standardised form (eg, Peking-style routine) with high-intensity movements (eg, use of lower stances).