Background and purpose: Tai chi has been suggested as a potential effective intervention for improving function and wellbeing in breast cancer patients. This systematic review evaluated the current evidence for the effectiveness of tai chi in patients with breast cancer. Methods: Randomized Controlled Trials (RCTs) evaluating the effects of tai chi in breast cancer patients were identified through searches in OVID MEDLINE, AMED, EMBASE, CINAHL, Cochrane Central Register of Controlled Trials, CNKI, VIP, and Wanfang Data, up to June 2019. Meta-analyses were performed for results syntheses. Results: Sixteen RCTs involving 1268 participants were included in this review. It was demonstrated that tai chi is no different from conventional supportive care interventions in improving fatigue, sleeping quality, depression or body mass index at either 3 months or 6 months; however it significantly improves overall quality of life (QoL) at 3 months. Moreover, tai chi, when offered as an adjunct to conventional therapy, is more effective in improving fatigue at 3 months, and QoL at 3 months and 6 months compared to conventional therapy alone. Conclusion: Tai chi shows no improvement in fatigue compared with conventional supportive interventions, but it significantly relieves fatigue symptom for breast cancer patients when used with conventional supportive care interventions. Tai chi versus conventional supportive care interventions, and as an adjunct to conventional therapy is effective in improving QoL for breast cancer patients.