The purpose of the present study is to investigate the clinical efficacy of traditional Chinese medicine (TCM) in treating breast cancer patients after mastectomy. We searched EMBASE, CENTRAL, MEDLINE, Chinese Biomedical Database, Chinese National Knowledge Infrastructure, Chinese Scientific Journal Database (VIP), and PubMed to collect randomized controlled trials of TCM in treatment of breast cancer patients after mastectomy. Quality of the methodology was assessment in accordance with Cochrane 4.2.2 Handbook. All patients were divided into two groups: TCM group (TCM only or TCM plus conventional treatment) and control group (conventional treatment only). Effects of TCM on short-term clinical outcome, long-term survival rate, and incidence of adverse reaction were compared between the two groups. Twenty-nine studies were included in this meta-analysis, involving a total of 3142 breast cancer patients. Meta-analyses showed that TCM could improve short-term treatment efficacy (Z = 7.67, RR = 1.59, 95 % cl [1.41–1.80], P < 0.00001), extend 3-year (Z = 5.47, RR = 1.26, 95 % cl [1.16–1.37], P < 0.00001) and 5-year (Z = 5.53, RR = 1.17, 95 % cl [1.11–1.24], P < 0.00001) survival, reduce the incidence of adverse reactions in breast cancer patients after mastectomy. TCM provides beneficial and complementary effects in the treatment of breast cancer patients after mastectomy.