Objectives: we used a quantitative method to systematically synthesize the emerging literature and critically evaluate the effects of Baduanjin on depression and anxiety in people with physical or mental illnesses. Additionally, we determined if the number of total Baduanjin training sessions is associated with decreased anxiety and depression levels. Methods: both English and Chinese databases were searched for potential studies published between January 1982 and October 2017. The eligible randomized controlled trials were considered for meta-analysis. Effect size (Hedge’s g) was computed for the pooled effects while the random-effect model was set. For moderator analysis; Subgroup meta-analysis for categorical variables and meta-regression for continuous variables were performed. Results: the aggregated result has shown a significant benefit in favour of Baduanjin on anxiety (Hedge’s g = −0.99; CI −1.63 to −0.74) and depression (Hedge’s g = −1.07; CI −1.3 to −0.83). For continuous potential moderators; meta-regression indicated a significant effect for total hours in Baduanjin practice ( β = −0.0053; 95% CI −0.009 to −0.0014; p = 0.008). With regard to depression; meta-regression indicated a significant effect for total sessions of Baduanjin practice ( β = −0.0023; 95% CI −0.006 to −0.0004; p = 0.028). Conclusions: the encouraging findings indicate the efficacy of Baduanjin exercise in reducing depression and anxiety symptoms in people with physical or mental illnesses. However; the results should be interpreted with caution because of existing methodological limitations (e.g., high risk of bias; Baduanjin combined with other behavioral interventions; and heterogeneity of control groups).