The polycomb group protein enhancer of zeste homolog 2 (EZH2) is regarded as a tightly linking oncogene in many types of cancer. However, the prognostic role of EZH2 in breast cancer (BC) still remains controversial. Our study aimed to evaluate the clinical and prognostic relevance of EZH2 in BC patients based on published studies. 11 studies totally containing 2330 patients (1052 EZH2-positive and 1278 EZH2-negative) were included in our meta-analysis. Our data showed that EZH2 over-expression was significantly associated with estrogen receptor (ER) negativity [OR=0.227, 95% CI=0.174-0.297, P=0.000], progesterone receptor (PR) negativity [OR=0.454, 95% CI=0.300–0.687, P=0.000], human epidermal growth factor receptor type 2 (HER-2) positivity [OR=1.846, 95% CI=1.366–2.496, P=0.000], invasive ductal cancer (IDC) [OR=2.237, 95% CI=1.489–3.361, P=0.000], race (Caucasian) [OR=0.707, 95% CI=0.522–0.957, P=0.025], high histological grade [OR=3.177, 95% CI=2.012–5.014, P=0.000] and triple-negative status (TNBCs) [OR=5.380, 95% CI=1.065–27.187, P=0.042], which led to a poor OS rate in BC [RR=2.193, 95% CI=1.495–3.217, P=0.000]. In conclusion, EZH2 participated in the progression of BC as a putative factor, and over-expression of EZH2 was distinctly correlated with a poor patient survival. EZH2 may serve as a prognostic biomarker and target in BC patients.